Post: May 15, 2026

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The Science Behind Plant Partnerships

It’s not magic; it is ecology in action

Rae Barto

By Rae Barto, Skagit County WSU Extension Master Gardener

Companion planting, the practice of growing different plant species together for mutual benefit, has long been part of gardening traditions across cultures. Historically, it has been framed through folklore, anecdote, and trial and error. But in the last two decades, scientific research has begun to validate, refine, and sometimes debunk these claims.

Modern researchers increasingly view gardens and farms as ecosystems rather than isolated plant beds. Companion planting is best understood as a form of polyculture, where multiple species create a more biodiverse and resilient environment. This biodiversity enhances nutrient cycling, reduces pest pressure, improves water retention, and carbon sequestration.

At its core, companion planting operates through several scientifically documented mechanisms.

Resource partitioning involves physical competition between plants. Plants with different growth habits, root depths, or nutrient requirements can coexist more efficiently than those competing for identical resources. Studies using isotope tracing have demonstrated that companion plantings access different soil layers and nutrient pools, thereby reducing competition.

Allelopathy — the chemical interaction between plants — represents one of the most studied aspects. Plants release various compounds through their roots, leaves, and decomposing matter that can either inhibit or promote the growth of nearby species. Research is identifying specific chemicals responsible for these interactions, providing a biochemical explanation for traditional planting combinations.

The attraction and repulsion of insects through companion planting is getting a lot of attention, and agricultural research proves plants produce volatile organic compounds (VOCs) that can either deter harmful insects or attract beneficial predators and pollinators. Aromatic plants can confuse or mask host plant odors, reducing pest pressure. They are typically short-range, not garden-wide.

Nitrogen Fixation: The Three Sisters and Beyond

Perhaps the most scientifically validated companion planting system is the “Three Sisters” combination of corn, beans, and squash, practiced by Indigenous peoples of the Americas for centuries. Research has confirmed that leguminous beans form symbiotic relationships with rhizobia bacteria, converting atmospheric nitrogen into plant-available forms that benefit neighboring crops.

While these benefits come primarily after the legume decomposes, planting beans next to corn (a heavy nitrogen feeder) allows the corn roots to obtain a trickle of nitrogen from the beans during the growing season. The beans utilize the corn stalks as natural trellises, while the broad squash leaves create living mulch that suppresses weeds and retains soil moisture, effects quantified through controlled field experiments.

Pruning Shrubs for the Home Gardener

May Know & Grow

Free. No registration required.

Presentor: Anne Kurt, Skagit County WSU Extension Master Gardener and Certified Master Pruner

Tuesday, May 19, 2026 ~ 1 p.m.

Sakuma Auditorium
16650 SR 536, Mount Vernon, WA 98273

Come learn some simple seasonal pruning tips to encourage the health and appearance of your garden shrubs. Learn to identify growth habit and determine the right time to prune and how. You will gain confidence and your garden will thrive.

Photo © Skagit County Master Gardener Foundation

Modern research has expanded our understanding of nitrogen-fixing partnerships beyond traditional combinations. Studies have documented beneficial relationships between leguminous cover crops and subsequent plantings with measured increases in soil organic matter and nitrogen availability lasting multiple growing seasons.

Pest Management through Plant Chemistry

Scientific investigation of companion planting for pest control has revealed sophisticated chemical defense networks. Brassicas (cabbage family plants) produce glucosinolates — sulfur-containing compounds that break down into pest-deterrent chemicals. Research has shown that these compounds can reduce populations of aphids, flea beetles, and other common garden pests when brassicas are interplanted with susceptible crops.

Beneficial Insect Attraction and Habitat Creation

Companion planting’s role in supporting beneficial insects has been thoroughly documented through field studies and insect population surveys. Flowering companions provide nectar and pollen sources that sustain parasitic wasps, predatory beetles, and other natural pest controllers through the growing season.

Research has shown that gardens with diverse flowering plants maintain higher populations of beneficial insects, leading to measurable reductions in pest damage. Studies tracking parasitoid wasp populations have demonstrated direct correlations between the presence of nectar-producing plants and improved biological pest control.

Habitat diversification through companion planting creates microclimates that support beneficial species. Research has documented how varied plant heights, leaf textures, and bloom times provide overwintering sites, hunting grounds, and nesting opportunities for natural pest predators.

Aromatic herbs like basil, rosemary, and thyme have been studied extensively for their pest-repelling properties. Laboratory and field studies have identified specific essential oils and their concentrations that effectively deter insects. For example, research has demonstrated that basil planted near tomatoes can reduce populations of hornworms and whiteflies by releasing volatile compounds such as eugenol and linalool.

Save the Date:

Discovery Garden Open House

Celebrating 30 years of education, inspiration and dedication to the community

Saturday, June 27 ~ 10 am – 2 pm
Free Admission and Parking
Discovery Garden
16602 State Route 536, Memorial Highway, Mount Vernon

Soil Health and Nutrient Cycling

One of the most significant advances in understanding companion planting comes from soil microbial ecology. Plants shape the microbial communities around the roots, and when species are grown together, these communities interact in complex ways.

Scientific studies of companion planting’s effects on soil health reveal complex underground interactions.

Mycorrhizal networks
The symbiotic relationship between plant roots and beneficial fungi, called a mycorrhizal network, can be enhanced through strategic plant combinations. Research using molecular techniques has shown how certain companion plants can expand these fungal networks, improving nutrient uptake and plant resilience.
Root exudate interactions
The carbon-rich compounds released by roots have been studied extensively, revealing how different plants can modify soil chemistry to benefit neighbors. For example, research has shown that certain plants release organic acids that help solubilize phosphorus, making this essential nutrient more available to companion plants with different root chemistries.
Carbon sequestration
The process by which plants capture and store atmospheric carbon dioxide (CO2) is called carbon sequestration. Studies have shown that soil organic matter improves with diverse plantings. Research demonstrates that polyculture systems often store more carbon in soil than monocultures, thereby contributing to long-term improvements in soil fertility and structure.

Limitations and Considerations

Scientific research also reveals important limitations of companion planting.

Allelopathic inhibition
A biological phenomenon where plants release chemical compounds (allelochemicals) into the environment that suppress the germination, growth, or reproduction of neighboring plants or microorganisms can occur when incompatible plants are grown together. Studies have documented how certain combinations can reduce yields rather than improve them.

Carrot and chive studies have shown that chives can repel carrot rust flies through the release of sulfur compounds; while differing root depths allow effective resource use. Photo © Adobe Stock

Competition
The effects of competition must be considered, as research shows that plants grown too closely can compete for water, nutrients, and light regardless of species compatibility. Scientific studies emphasize the importance of proper spacing and timing in companion planting systems.
Environmental variability
Research demonstrates that soil type, climate, and local pest populations can influence the effectiveness of plant combinations. This underscores the importance of adapting companion planting strategies to local conditions.
Evidence-Based Companion Combinations
Tomatoes and basil have been studied extensively, and research has confirmed that basil can deter certain pests.

Carrot and chive studies have shown that chives can repel carrot rust flies through the release of sulfur compounds; while differing root depths allow effective resource use.

Lettuce and tall plants demonstrate the shade tolerance principle, with research showing that partial shade can extend lettuce growing seasons and reduce bolting in hot weather.

Practical guidance:

• Focus on increasing diversity, not specific “magic” pairings. Polycultures reduce pest outbreaks and improve soil health.
• Include flowering plants to attract and support beneficial insects.
• Use legumes for nitrogen fixation and to build soil health; interplant beans, peas, or clover with nitrogen-demanding crops.
• Combine plants with complementary root systems; mix deep-rooted, shallow-rooted, and tap-rooted species.
• Use the plant’s physical structures — tall plants can support climbers or provide shade.
• Incorporate cover crops — oats, buckwheat, winter rye, and cowpeas improve soil structure and fertility.
• Focus on soil microbiology — choose combinations that enhance microbial diversity and nutrient cycling.
• Observe and adapt, local conditions matter.
• Combine with other practices, such as crop rotation and soil management.

The science of companion planting validates many traditional practices while providing a deeper understanding of the mechanisms involved. Through scientific research on plant chemistry, soil interaction, and ecological relationships, we now have evidence-based explanations for why certain plant combinations work effectively together.

By understanding the science behind companion planting, gardeners can harness these natural relationships to create thriving, resilient gardens that work with, rather than against, ecological principles. As research continues to reveal new insights into plant interactions, companion planting enables gardeners to combine traditional knowledge with modern science to create a more sustainable, productive garden.

Companion planting is a scientifically supported practice rooted in ecology, soil biology, and plant physiology. While not all traditional pairings hold up under scrutiny, many do, and modern research continues to uncover the mechanisms behind successful plant partnerships.

Companion planting works best as part of a holistic system rather than a standalone solution. Companion planting is not magic; it is ecology in action.

References and Resources

Chalker-Scott, L. (2023). Gardening with Companion Plants (Home Garden Series). Washington State University Extension.

Walliser, J. (2020). Plant Partners: Science-based Companion Planting Strategies for the Vegetable Garden. Storey Publishing, LLC.

James, D. (2014). Beneficial Insects, Spiders, and Other Mini-Creatures in Your Garden. Washington State University Extension., Pub. #EM0673.

University of California (2018). Insectary Plants, Integrated Pest Management, Agriculture and Natural Resources.

ABOUT THE AUTHOR: Rae Barto is a Skagit County WSU Extension Master Gardener, Class of 2023. Her love of plants includes anything green and growing, especially anything that can be used in cooking. She has been experimenting with companion planting for several years in her own garden. She is the coordinator of the medicinal section of the Herb Garden and is a frequent volunteer in the Plant Clinic in Burlington. 

Questions about home gardening or becoming a master gardener may be directed to Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the Skagit County WSU Extension website.

Washington State University Extension helps people develop leadership skills and use research-based knowledge to improve economic status and quality of life. Cooperating agencies: Washington State University, US Department of Agriculture, and Skagit County. Extension programs and policies are available to all without discrimination. To request disability accommodations contact us at least ten days in advance.

Post: May 1, 2026

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Ready to Go Shopping?

Know your yard’s microclimates before you head to the plant sale

 
Kari Ranten

Perhaps nothing thrills a home gardener more than the abundance of plants available for sale in spring. A walk through a nursery lures the gardener to marvel at beautiful perennial blooms; to desire the look, texture, and color of a tree or shrub; or to seek out the amazing native plants that call the Pacific Northwest home.

With so many beautiful choices, it’s easy to quickly fill a wagon with one (or three) of everything that looks beautiful in the moment. Before making those impulse buys, take some time to think about what will thrive in your landscape. A little homework will improve the success rate for your new plants. Research your local microclimates and keep the unique details of your yard in mind to make careful selections of the right plants for the right places – a standard master gardener mantra.

Home gardeners in northwest Washington share the Zone 8b assignment on the U.S. Department of Agriculture’s (USDA) Plant Hardiness Zone map. Type in your zip code in the map tool to learn more. This resource provides an excellent overview of plants’ overall frost tolerance and offers a broad overview of the area’s climate.

Gardeners should pair this up with localized information and knowledge of their own property.

Sunset’s Western Garden Book defines a microclimate as “a small area (such as a backyard or even a portion of it) with a slightly different climate than that of its larger surroundings. . . Plants that might not survive in a specific climate zone may grow well in the right microclimate.”

Individual yards likely have one or more unique microclimates that the home gardener should learn about and understand. Microclimates include areas of shade, sun, wind, moisture, soil, and topographic features such as elevation. In northwest Washington, proximity to rivers, lakes, and the Puget Sound also plays a role. In addition, structures, pavement, and fences can create varying conditions.

Armed with this information, gardeners can review plant qualities online or at the library ahead of time, take a list of desired plants or qualities along for the shopping trip, and make smart purchases. Once at the nursery or plant sale, shoppers will benefit from a close evaluation of plant tags (with hardiness zone compatibility and other notes for proper planting conditions) and the option to talk to the experts.

Start by doing your research

Evaluate your yard by drawing a simple map and taking notes. Observe the direction each area faces, note any low-lying areas or slopes, and learn more about the soil quality. Pay attention to the location of structures or hard surfaces that may store heat on a sunny day, creating overnight warm spots, as well as large vegetation that may bring a sphere of shade and cooler temperatures. Perform timed checks every few hours (say 9 a.m., noon, and again at 3 p.m.) during the day to monitor sun and shade patterns. Be aware of elevation and rainfall.

32^nd Annual Plant Fair Set for
Saturday, May 9 ~ 8 am – 2 pm
at the Skagit County Fairgrounds

Kick off your spring plant-buying season at the Skagit County Master Gardener Foundation Plant Fair set for 8 a.m. to 2 p.m. on Saturday, May 9, 2026, at the Skagit County Fairgrounds in Mount Vernon. The event will feature more than 10,000 plants grown or tended by Skagit County WSU Extension Master Gardeners for success in northwest Washington. More than 50 varieties of tomatoes and thousands of annuals, vegetables, herbs, perennials, trees, shrubs, berries, and more will be available. In addition, dozens of vendors will be on site with many offering plants and garden-related items. Admission and parking are free. Read the full press release>

Customers can plan ahead and prepare a shopping list by reviewing lists of plants that master gardeners will offer:

• List of tomato varieties>
• Lists of greenhouse-grown annuals, flowers, and herbs and Perennial Plant House propagated and grown perennials, trees, berries, figs and grapes>

The Skagit County WSU Extension Master Gardener Program helps our communities with their gardening needs by providing science-based education, answering plant questions, and helping with plant problems. Proceeds from the annual Plant Fair benefit the nonprofit Skagit County Master Gardener Foundation, which supports the Skagit County Master Gardener Program.

Soil tests from several locations in the yard will help you understand what your soil may need to support healthy plants.

Washington State University’s Ag Weather Net provides regional climate information from several locations in Skagit and surrounding counties about wind, temperature, and precipitation information. A home garden weather station can help gather and archive data at your specific location.

The University of California Agriculture and Natural Resources Marin County Master Gardeners provides a detailed spreadsheet to help assess microclimates and the factors to consider when planning a garden or landscape.

Another research opportunity is to observe thriving landscapes or yards in your neighborhood or community, and to visit botanical gardens in the region to see and learn about plants that thrive in the northwest environment. The 30-plus garden “rooms” of the Skagit County WSU Extension Master Gardener Discovery Garden on Memorial Highway west of Mount Vernon offer many ideas and inspiration for gardens with themes ranging from naturescape and shade to dryscape or succulents. The Discovery Garden is open daily from dawn until dusk.

Say you have a one-third-acre lot with a single-level home in central Skagit County: 

Watch the frost and snow patterns. It’s not uncommon for the north side of the house to harbor frost eight to 10 feet north of the structure for hours after the white frosty layer has melted from the rest of the yard. Snow can remain in place for days in that swath. Plants in that area must be cold and moisture-tolerant. That’s a microclimate. Well-established plants such as a June-blooming rhododendron or a David viburnum (Viburnum davidii) can continue to thrive. Adding shade-loving ferns like Asian saber fern (Polystichum neolobatum), western sword fern (Polystichum munitum), or dragon tail fern (Asplenium ebenoides) along with a couple of perennials like bleeding heart (Dicentra spectabilis) and Solomon’s seal (Polygonatum) add texture and interest in the spring and appear year over year.

Pruning Shrubs for the Home Gardener

May Know & Grow

Free. No registration required.

Presentor: Anne Kurt, Skagit County WSU Extension Master Gardener and Certified Master Pruner

Tuesday, May 19, 2026 ~ 1 p.m.

Sakuma Auditorium
16650 SR 536, Mount Vernon, WA 98273

Come learn some simple seasonal pruning tips to encourage the health and appearance of your garden shrubs. Learn to identify growth habit and determine the right time to prune and how. You will gain confidence and your garden will thrive.

Photo © Skagit County Master Gardener Foundation

The south side of the house can be quite a different microclimate. A large, south-facing patio and the house’s siding would make a true hot spot, even on warm spring days, much less on a 90-degree summer afternoon. A few plants in hanging baskets could thrive through the summer without an irrigation system. A raised bed or large pots tucked next to a south-facing wall or fence provide warmth and light reflection that tomatoes love, yielding lots of delicious fruit, steps away from the kitchen.

With careful plant selection and regular (sometimes twice daily) watering, larger pots filled with annuals and perennials can produce a beautiful abundance of color for the season. Plants with bright red and orange flowers, such as firecracker plant (Cuphea hybrid), Mexican lobelia (Lobelia laxiflora), and lantana (Verbenaceae) attract a number of pollinators including hummingbirds.

Make good plant selections. Create a list of plants that suit the landscape’s microclimates. This includes trees, shrubs, perennials, and annuals. Photos © Adobe Stock

Based on research and data gathered for your yard, you have options:

1. Make changes to manage a microclimate:

• Consider adding organic matter to improve soil moisture capacity or install an irrigation system for dry areas.
• Use raised beds for plants that need drainage and warmer soil temperature.
• Look into drains for slopes to allow water to flow in wet areas.
• Move and group plants that appreciate similar conditions.
• Protect more fragile plants with a shelter of tall plantings or a fence.

2. Make good plant selections. Create a list of plants that suit the landscape’s microclimates. This includes trees, shrubs, perennials, and annuals. Gardeners have access to a variety of resources for plant lists, including:

• Sunset’s Western Garden Book offers 30 lengthy lists with photos and plant details based on climate qualities, including sun, shade, dry areas, moisture lovers, and wind resistance.
• Great Plant Picks, the educational program of the Elisabeth C. Miller Botanical Garden in Seattle, offers many lists to support plant selections for gardeners living west of the Cascade Mountains from Eugene, Oregon, to Vancouver, British Columbia, Canada. Lists focus on drought tolerance, sun and shade, containers, and more.
• The Washington State Noxious Weed Control Board offers a printable list of noxious weeds.
• The Washington Native Plant Society provides information on invasive non-native plants that compete with native plants, plus lists on the plethora of Washington native plants that are special to Washington. 

Armed with details about your landscape, soil, light, and weather, along with a list of plants that are of interest, head out to the nursery or local plant sale with a disciplined plan to start with. Ask questions. Look at lots of plants. Make a measured selection of choices. Take those home, size up your status and, if needed, make another trip – oh, joy! The fun can stretch over a period of growing years as you watch and enjoy the maturation of your well-planned garden spaces tailored to your unique microclimates. 

References and Resources

City of Seattle Public Utilities. (2010) Natural Lawn & Garden Series: Choosing the Right Plants for a Beautiful, Trouble-Free Garden.

Elisabeth C. Miller Botanical Garden. (2026) Great Plant Picks.

McMoran, D, Huter, S. and Buller, S. (2015) How to Determine your Garden Microclimate. Washington State University Extension Bulletin FS181E.

Sunset Western Garden Book (2007) Sunset Publishing Corporation. Menlo Park, CA. 94025

University of California Agriculture and Natural Resources Marin County Master Gardeners. (2026) Garden Site Microclimate Evaluation Form.

U.S. Department of Agriculture’s (USDA) Plant Hardiness Zone Map. (2026) https://planthardiness.ars.usda.gov/

Washington Native Plant Society

Washington State University’s Ag Weather Net

ABOUT THE AUTHOR: Kari Ranten is a retired journalist and health care communicator who became a certified Skagit County WSU Extension Master Gardener in 2024.

Questions about home gardening or becoming a master gardener may be directed to Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the Skagit County WSU Extension website.

Washington State University Extension helps people develop leadership skills and use research-based knowledge to improve economic status and quality of life. Cooperating agencies: Washington State University, US Department of Agriculture, and Skagit County. Extension programs and policies are available to all without discrimination. To request disability accommodations contact us at least ten days in advance.

Planting, growing and maintaining blueberries

Growing blueberries: Start with the right soil to get “superfood” results

How to choose blueberries well suited for success in the Pacific Northwest

Posted July 4, 2025

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By Kari Ranten, Skagit County WSU Extension Master Gardener

Kari Ranten

Blueberries are a staple of Skagit County’s thriving commercial agricultural economy and are an increasingly popular plant and crop for northwest home gardeners.

Commercially, Washington leads the nation in blueberry production, with 26 percent of U.S. blueberries generating a revenue of $205 million, according to the U.S. Department of Agriculture (USDA-NASS.2025). Blueberry acreage in Skagit County increased eightfold since 2000. In 2023, 4,800 acres of blueberries were grown commercially in Skagit County, ranking third in crop acreage behind only field crops and potatoes, according to Washington State University Extension Skagit County’s Crop Acreage and Yield Report.

These strong statistics show that northwest Washington is an excellent growing environment for home and commercial production of blueberries, yielding a delicious summertime fruit crop or serving as a sturdy, attractive ornamental addition to the home landscape.

Blueberries have gained popularity among consumers for their nutritional qualities and are recognized as a “superfood,” offering an excellent source of essential nutrients, vitamins C and K, and dietary fiber. Blueberries are also a nutritional source of valuable “phyto-components,” contributing to antioxidants and anti-inflammatory qualities.

For those interested in growing blueberries in the home garden, there are some decisions and preparatory steps to take to get ready for planting from January to March.

Common varieties
Of the five main types of blueberries grown in the United States, northern highbush blueberries (Vaccinium corymbosum L.) are most common in Washington. These deciduous, perennial shrubs are shallow-rooted, take six to eight years to reach full production, and varieties can reach five to nine feet in height.

Researchers at WSU Mount Vernon Northwestern Washington Research & Extension Center (NWREC) play a vital role in working with commercial blueberry growers. Chakradhar Mattupalli, assistant professor of plant pathology, leads the Berry and Potato Pathology Program, conducting research and extension activities addressing the biology and management of diseases of highbush blueberry and potato crops. He provided guidance and resources in the preparation of this article. For more information about Mattupalli’s research, go to Berry and Potato Pathology | Washington State University

NWREC is one of four WSU Research Centers operated by the College of Agricultural, Human, and Natural Resource Sciences, housing nine research programs, extension outreach, and research affiliates. The research center works to solve plant-related problems and develop cost-effective and environmentally sound plant production practices based directly on results from experimental field, greenhouse, and laboratory research trials.

The publication “Blueberry Cultivars for the Pacific Northwest” notes that half-high blueberries, the result of crosses between northern highbush and lowbush blueberries, can also grow in the region and reach three to four feet tall. The cultivars are also used as attractive landscape plants and are suited to container production.

The NW Fruit Garden, next to the Discovery Garden on Memorial Highway in Mount Vernon, provides home gardeners with an excellent illustration of 30 blueberry varieties suitable to the local environment. The garden is maintained by volunteers, including Beth Jones, a NW Fruit volunteer since 2019, who leads the blueberry team charged with caring for 122 plants, some more than 20 years old.

Northern Highbush “Duke”

Northern Highbush “Draper”

Northern Highbush “Bluejay”

Start by selecting a location and testing soil acidity

Home gardeners can start by selecting the right location and soil for blueberry bushes. Blueberries require acidic soil with a pH of 4.2 to 5.5, similar to rhododendrons and azaleas, according to a 2025 presentation to Skagit County Master Gardeners trainees by Lisa Wasko DeVetter, associate professor of small fruit horticulture at Washington State University’s NWREC in Mount Vernon. Soil can be lab tested for pH, and if needed, acidification can be enhanced. A publication by Oregon State University Extension titled “Acidifying Soil for Crop Production West of the Cascade Mountains” provides a good resource on evaluating and enhancing soil acidity.

Because of the acidic soil needs of blueberries, home gardeners will need to plan ahead and prepare the space and soil before the arrival of the early spring planting season.

Blueberries can also be grown in containers and flourish in the full sun.

Plant selection, pollination, and care
Home gardeners should select two- to three-year-old plants (when shopping, ask at the nursery about plant age) and be on the lookout for those that are disease and heat-resistant “Legacy”, “Rubel”, and “Liberty”, have shown resistance to common diseases and rising summer temperatures in the NW Fruit Garden.

Plant blueberries from January to March, spacing three feet apart, in holes large enough to handle all of the shallow roots and allow three to four inches of soil to cover. Once established, blueberry plants are quite sturdy, with most producing fruit for 20 years.

While northern highbush blueberries are self-fertile, experts advise home gardeners to plant at least two different cultivars with overlapping bloom times in proximity to one another to benefit from cross-pollination and larger, earlier fruit.

All northern highbush blueberries are compatible with each other for cross-pollination.

Remove all flowers during the first year or two after planting to prevent fruit from setting and to give plants time to mature and enhance future yield.

Fertilize annually with a focus on nitrogen. For more information, see Oregon State University Extension publication EM 8857 titled “Nutrient Management for Blueberries in Oregon.” 

Blueberries require regular, supplemental watering from May to August and annual mulching with untreated wood chips.

Interested in Becoming a Master Gardener?

Application period is now open through August 15, 2025.

WSU has recently launched a new training platform called Washington Green School, designed to provide comprehensive research-based horticulture and environmental stewardship education. The Washington Green School offers two distinct tracks:

• Washington Gardener Certificate Track
  This option is ideal for individuals seeking to enhance their gardening skills without the commitment of volunteering. This self-paced, online-only course provides a certificate upon successful completion.
• Extension Master Gardener Volunteer Track
  This track is for those interested in becoming certified WSU Extension Master Gardener volunteers and includes the Green School online coursework, in-person, local volunteer training, and a commitment to volunteer service hours.

For more information, go to https://skagitmg.org/home/green-school/

To apply for the Skagit County WSU Extension Master Gardener Program, go to https://extension.wsu.edu/skagit/mg/apply/

Prune each year in winter or early spring to eliminate any dead or weak shoots and select two to three new canes to retain for the next season. Prune carefully to retain the desired shoots, creating a vase shape that opens up the middle of the plant to provide air and light. Half-high cultivars do not need to be pruned as severely or as regularly as highbush types.

Healthy, established blueberry plants can yield more than one gallon of fruit per plant.

Blueberry plants can decline over time and should be replaced when they stop sending up new shoots during the growing season.

Pests and common diseases
A variety of pests and diseases can impact blueberry bushes and fruit.

Birds enjoy feasting on blueberries. To protect the fruit harvest from birds, home gardeners may want to cover plants with fine netting mounted on a frame and anchored to the ground from mid-June through harvest completion in August. If the bushes are growing for landscape purposes, let the birds have a summer snack.

Spotted wing drosophila, aphids, scale insects, root weevils, inchworms, and fruit worms can damage blueberry plants and fruit. To prevent or manage such infestations, refer to WSU’s publication “Growing Small Fruits in the Garden.”

In northwest Washington, blueberries are impacted primarily by two diseases: mummy berry and botrytis blight or gray mold.

Mummy berry is easily identified by the home gardener in the mid- to late- stages as the mature mummified fruit appears gray, shriveled, hard, and inedible. The disease is caused by a fungus that infects young flowers and vegetative buds in spring. About three weeks after primary infection, a brownish-gray mass of spores develops on blighted flower stalks and leaves that are spread by wind, rain, and honeybees (pollinators) to healthy flowers.

To manage the disease, the home gardener must remove the mummified fruit from the plant and lift it off the ground, add about two inches of mulch around the plants, and regularly disturb the soil during the spring. Healthy fruit can be harvested and used. At season’s end, clean the area to prevent infected berries from overwintering.

Blueberries, strawberries, and raspberries, especially on the west side of the Cascades, are affected by botrytis blight and gray mold. The cool and wet weather in western Washington is conducive to the development of this disease. Pruning creates airflow in the plant canopy, and reduced moisture on the foliage or fruit can help slow down the fungal growth.

REFERENCES AND RESOURCES:

Brun, C. A., DeVetter, L., and Benedicts, C. (2016) Growing Small Fruits in the Home Garden. Washington State University Extension Home Garden Series. Publication #EM103E

Finn, C., Strik, B., and Moore, P. (2024) Blueberry Cultivars for the Pacific Northwest. Oregon State University Extension Service. PNW #656

Hart, J., Strik, B., White, L., and Yang, W. (2020) Nutrient Management for Blueberries in Oregon. Oregon State University Extension Service. EM 8918. 

Horneck, D., Hart, J. Stevens, R., Petrie, S., and Altland, J. (2004) Acidifying Soil for Crop Production West of the Cascade Mountains (Western Oregon and Washington). Oregon State University Extension Service. EM 8857. 

Pscheidt, J.W., and Ocamb, C.M. (2025a). Blueberry (Vaccinium corymbosum)-Mummy Berry.  Pacific Northwest Plant Disease Management Handbook. Oregon State University. 

Pscheidt, J.W., and Ocamb, C.M. (2025b). Blueberry (Vaccinium corymbosum)-Botrytis blight. Pacific Northwest Plant Disease Management Handbook. Oregon State University.

Washington State University Northwestern Washington Research and Extension Center. (2025) Berry and Potato Pathology.

Washington State University Skagit County Extension Skagit County Agricultural Statistics. (2024) Crop Acreage and Yield Report.

Yan, L. (2023) Blueberries and Health. USDA Agricultural Research Service.

ABOUT THE AUTHOR:

Kari Ranten is a retired journalist and health care communicator who became a certified Skagit County WSU Extension Master Gardener in 2024. 

Questions about home gardening or becoming a master gardener may be directed to Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the Skagit County WSU Extension Master Gardener website.

Washington State University Extension helps people develop leadership skills and use research-based knowledge to improve economic status and quality of life. Cooperating agencies: Washington State University, US Department of Agriculture, and Skagit County. Extension programs and policies are available to all without discrimination. To request disability accommodations contact us at least ten days in advance.

Mark Your Calendar!

Skagit County Master Gardener Plant Fair is Saturday, May 10

Anticipation is Building for the Annual Event on Mother’s Day Weekend

By Kari Ranten, Skagit County WSU Extension Master Gardener

Kari Ranten

Featuring thousands of plants for sale, the Skagit County Master Gardener Plant Fair is a local celebration of spring and gardening.

Gardeners across the region count on the plant fair as a place to purchase quality plants and look forward to gathering inspiration for the coming growing season. Did you know that all of the tomatoes – more than 3,600 plants – available at the plant fair are grown from seed by volunteer WSU Extension Master Gardeners? Not only that, the varieties grown are chosen because they are ideal for our climate.

The 31st annual Plant Fair is set for 8 a.m. to 2 p.m. on Saturday, May 10, 2025, at the Skagit County Fairgrounds. The event and parking are free, enter through the south gate of the fairgrounds. Attendees are encouraged to bring a wagon or wheelbarrow to help transport their selections. Boxes are available at the site and customers can leave purchased plants at a free plant parking area monitored by volunteers as they continue to shop and enjoy the plant fair. An ATM will be available on site.

3,600 Tomato Plants – 2,000 Flowering Annuals
2,000 Vegetable and Herb Starts
Hundreds of Perennials and Native Plants
Small Fruits: Grapes, Figs, Currants, Berries

“As an organization and a community of people who live and love all things gardening, we are looking forward to this amazing annual event,” said Master Gardener Claire Cotnoir, who, along with her husband and fellow Master Gardener Hank Davies, co-chairs the plant fair. “This is our way to inspire all gardeners by offering quality plants suited to growing successfully in our region. We enjoy the opportunity to share information and enthusiasm for gardening, along with educating the public about how to embrace gardening as a way to care for and protect the environment.”

The plant fair will offer thousands of plants for sale, including vegetables, tomatoes, herbs, perennials and native plant varieties. Most of the plants are grown or propagated by master gardener volunteers.

The plant fair is truly a highly anticipated event, as illustrated by those who waited in line at the gates last year. Some called their annual visit to the event a “Mother’s Day weekend tradition” for their family. One smiling woman, with a wheelbarrow in tow, proclaimed “It’s the only holiday I celebrate – Plant Fair Day!”

Need Tips on Growing Tomatoes?

Master Gardener Denny Organ, an expert in growing tomatoes in the region, will provide short workshop-style presentations with tips on planting, pruning and general care for tomatoes between 9 a.m. to noon on Saturday, May 10 at the Master Gardener Demonstration Booth. Between presentations, Denny will be available to answer one-on-one questions about growing tomatoes. Check at the master gardener information booth at the Plant Fair for specific times of the presentations.

In addition to plant sales, the Plant Fair will feature:

• More than 50 vendors will offer garden accessories, gifts, plants, garden art and hand-crafted items. Several food vendors will also be on site.
• Skagit County Master Gardeners will host an educational booth and display, with a focus on pollinators, firewise gardening and growing tomatoes.
• Master gardeners will staff a Plant Clinic at the fair to help address plant questions or concerns.
• Master gardeners will offer free tool sharpening, with a limit of one tool per customer.

The annual Skagit County Master Gardener Plant Fair is the primary fund-raising event run by the Skagit County Master Gardener Foundation (SCMGF). Proceeds enable the foundation to support master gardener outreach, events, education and activities. Beyond fundraising, the plant fair builds community awareness of the master gardener program, encourages community participation in gardening and growing local food, and inspires people to become master gardener volunteers.

Master gardener volunteers also maintain the Discovery Garden just west of Mount Vernon on Memorial Highway, which is open to the public daily as a showcase for the variety of plants that grow in the region.

Cherry, slicers, salad, paste, and dwarf are among the fifty tomato varieties available at the Plant Fair.

Now you own a lovely tomato plant. Read on to help your plant grow and thrive, producing delicious tomatoes throughout the season.

Soon to be a proud owner of a tomato plant? What’s next?

Many Skagit County Master Gardener Plant Fair customers are laser focused on one thing: Buying tomato plants. As they check out, with plants in hand, the question many have is what to do next with these amazing plants?

Past customers, many who have purchased tomatoes at the plant fair for several years running, express satisfaction with the product. Of course, each growing season is unique and 2024 presented some challenges with rain and cooler temperatures. Between the May plant fair and the end of the 2024 growing season, customers describe the tomato plants produced by master gardeners as healthy, hardy and offering a “really great yield.”

In the fall, master gardeners taste test 30+ varieties of tomatoes to select the varieties to grow for the Plant Fair.

Master gardeners grow all of the tomato plants from seed. The process begins in February to have them ready for the plant fair. Lights, heat mats and tender loving care help nurture the seeds to germination and on to developing into fledgling plants. As they grow, the tomatoes are transplanted into six-pack plugs, then four-inch pots and ultimately to the one-gallon pots available for sale.

Going into the plant fair, customers may check out the list of varieties available on the Skagit County Master Gardener website and make selections based on a desire for snacking, sauces, slicing and other tomato uses. All varieties are carefully chosen by master gardeners and tested for growing conditions in Skagit County. In addition, for a comprehensive A-Z listing of tomato varieties featuring go to the tomato selection tool on this website.

At the end of each season, master gardeners gather for a taste-test session of fruit from their plants to help inform future variety selection. Some of the varieties available for purchase at the plant fair will be marked as “Winner of Our MG Tomato Tasting Event.”

Tomatoes: What do I do next?
So, once you take home tomato plants at the mid-May plant fair, what should you do next to have success? Here are a few tips on how to plant and care for these fledgling tomatoes from master gardeners who head up the “Tomato Team” and other resources:

Hardening off: The tomato plants, in one-gallon pots, will have spent more than a month in an unheated greenhouse leading up to the plant sale. As temperatures warm, they will need gradual introduction to sunlight and the outdoors. Place the plants in a sheltered location near the house or other structure and expose the plants to indirect sunlight gradually. Start with one hour on the first day and add one hour each day, building up to a full day. Plants can tolerate direct sunlight after three to five days.

According to the Washington State University Extension Fact Sheet FS145E titled Growing Tomatoes in Home Gardens,“After a week, leave plants outside overnight. If temperatures drop below 50°F, keep them indoors . . . Do not plant them before the frost-free date for your area because spring frost can kill young tomato plants.” Plants should not be transplanted unprotected until nighttime temperatures stay above 45 to 50 degrees, which may not be until June, according to Vegetable Gardening in the Pacific Northwest by Seattle author Lorene Edwards Forkner.

If the people in the fun, creative hats (master gardeners) look a little giddy, it is because they have crossed the finish line, successfully raising nearly 10,000 healthy, happy plants for you to bring home and enjoy this summer.

Planting: Whether using a container or transplanting into the ground, plant in well-drained soil in a sunny location. Plant in a deep hole and cover the stem up to the bottom leaves with soil to inspire root growth and plant development.

Trench planting is also an option. Trench planting involves digging a trench about six inches deep, adding a tablespoon of super phosphate to the soil (well mixed), and laying the whole plant in the ground with only the very top of the plant exposed to the sunlight. For more information about trench planting, go to North Carolina State University Extension Publications, Growing Tomatoes in the Home Garden in the references below.

Growing in pots: Tomatoes do not like to be confined to small pots for too long. The master gardener tomatoes are sold in one-gallon pots, which will work for a while, however, be sure to have 10-gallon grow bags, pots, or buckets with holes drilled in the bottom at the ready when overnight temperatures are appropriate to transplant outdoors for the season. Remember, tomato plant roots can go more than six inches deep into the soil so the more room you give them in a pot the happier they will be. Also, consider growing determinate plants in pots and indeterminate in the ground if possible. Determinate plants top off at around five feet tall and are easier to grow in pots than indeterminate which are vining and will grow until fall frost. Another wonderful option available for pots or patio growing this year are dwarf varieties, also available at the plant fair.

Watering: Tomatoes will perform better if they are a little dry rather than soggy. For plants in pots, providing a plastic roof or clear plastic cloche to keep the rain off is helpful, but not required. “Water regularly and deeply since tomatoes are deep-rooted plants, but avoid overhead irrigation, which can encourage disease,” according to “Sunset Western Garden Book of Edibles.” Author Forkner suggests reducing watering near the end of the season to encourage fruit ripening.

Support: Indeterminate tomatoes, those that grow like vines, benefit from supports such as cages, trellises or pole supports. Determinate varieties are more compact and bushier, reaching a fixed height.

Light and exposure: In the Pacific Northwest, placing pots along a south-facing wall is best for tomato success. A garden space with full sun for at least six hours per day, according to the Washington State University Extension Fact Sheet FS145E.

Potential problems: Tomatoes can be impacted by a variety of diseases and pests. Research and select cultivars that are disease resistant. Washington State University Extension Fact Sheet FS145E lists a variety of potential problems, including:

• Late blight: The fungal disease appears as gray-green coloration on leaves, stems and fruit, turning to dark blotches on the fruit. The fact sheet suggests avoiding over watering, removing infected plants or plant parts when symptoms are noticed, but do not compost them. Give plants ample space to support air circulation.
• Slugs: Common in Western Washington, slugs can completely consume younger plants, damage foliage of more mature plants and cause “hollowing damage” on fruit. To protect plants, remove weeds and debris, encourage predators; hand-pick and kill slugs that feed at night and use chemical-based baits with caution.
• Blossom End Rot: According to the University of Wisconsin, Wisconsin Division of Horticulture Extension, this condition often occurs on the first fruits formed on plants. Initially, water-soaked spots (resembling small bruises) appear, most often on the bottoms of fruits and include dark, leathery, sunken areas on the blossom end of the tomato. This is caused by a lack of calcium uptake and conditions where there is too much or too little water. Water evenly and mulch the soil to retain moisture during dry periods. Avoid practices that would damage roots, such as cultivating too near plants thereby cutting roots, use a good Cal-Mag fertilizer and do not “wash” out soil nutrient with heavy over watering.
• An additional resource regarding pests and diseases with tomatoes is the University of Maryland Extension’s Key to Common Problems of Tomatoes

Harvest and use: Harvest when the fruit reaches mature color. Tomatoes can be used in a wide range of preparations from fresh to frozen or dried to canned. For more information, check out the National Center for Home Food Preservation (http://www.uga.edu/nchfp/) or Oregon State University Extension Service’s site focused on canning tomatoes and tomato products (https://extension.oregonstate.edu/catalog/pub/pnw300-s).

REFERENCES:
Fredericks, G., Cowan, J. and Daniels, C. (2014) Vegetables: Growing Tomatoes in Home Gardens. Washington State University Extension Fact Sheet #FS145E. 

Forkner, L. (2012) Vegetable Gardening in the Pacific Northwest. Portland, OR. Timber Press.

North Carolina State University Extension Publications, Growing Tomatoes in the Home Garden.

Skagit County Master Gardener Tomato Variety Selection Tool

Sunset. (2010) Sunset Western Garden Book of Edibles: The Complete A to Z Guide to Growing Your Own Vegetables, Herbs, and Fruits.” Menlo Park, California. Sunset Publishing Corporation.

Key to Common Problems of Tomatoes University of Maryland Extension.

Blossom End Rot. (2024) University of Wisconsin-Madison, Wisconsin Horticulture Division of Extension.

Washington State University CAHNRS and WSU Extension Hortsense.  

Looking Ahead to Summer-
Join us for a Free Open House
Saturday, June 28 – 10 am – 2 pm

Explore the three gardens in one location: the WSU Extension Master Gardener Discovery Garden, the NW Fruit Garden, and the Salal Native Plant Garden at the Discovery Day Open House. Talk to the volunteers that manage each of the gardens.

ABOUT THE AUTHOR:
Kari Ranten is a retired journalist and health care communicator who became a certified Skagit County WSU Extension Master Gardener in 2024.

Questions about home gardening or becoming a master gardener may be directed to Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the website: www.skagit.wsu.edu/mg

Washington State University Extension helps people develop leadership skills and use research-based knowledge to improve economic status and quality of life. Cooperating agencies: Washington State University, US Department of Agriculture, and Skagit County. Extension programs and policies are available to all without discrimination. To request disability accommodations contact us at least ten days in advance.

Tips to Making Strategic Vegetable Seed Selections

Helpful Ideas for Choosing What to Grow in the Vegetable Garden

By Kari Ranten and Cathy Markham, Skagit County WSU Extension Master Gardeners

Planning a vegetable garden for the upcoming growing season is the perfect indoor activity for the cold gray month of January in northwest Washington. Those plans all begin with the process of choosing the right seeds for the produce you want to plant, grow, harvest, eat, and preserve.

Shopping for seeds can be just as fun and educational as any step in the vegetable garden.

Giving a gardener a stack of seed catalogs is like the veritable “kid in a candy store.” These volumes, filled with colorful images and tempting descriptions of dozens of vegetables – from asparagus to zucchini – create a shopping experience like no other. As certified Skagit County WSU Extension Master Gardener Cathy Markham notes, “The problem is there are thousands of choices and, yet, that’s the fun part.”

The challenge in seed selection is to remain focused, strategic, and practical in making the right choices.

Start your research of seed options after making a list of favorite vegetables and evaluating your space, facilities, and skill level. Begin with learning how to read a seed description in a catalog, on a website, or a seed packet.
Photo © Cathy Markham, used with permission by Skagit County Master Gardeners

In our area warm-season crops such as tomatoes, peppers, eggplant, and melons need to be started indoors. Cathy uses a soil-blocking method (pictured above) to start seeds. This allow roots to grow vigorously without confinement and minimizes transplant shock.
Photo © Cathy Markham, used with permission by Skagit County Master Gardeners

Getting started
Here are some important considerations to help narrow down what seeds to purchase:

• Grow your favorites: Think about the produce that is most used and appreciated at the dinner table or preserved in the freezer or pantry. Putting a priority on these vegetables can help pare down the list of what to grow and the seeds to purchase. Cathy is a tomato aficionado, and pours over the seed catalogs and websites for her favorites and opportunities to try new varieties.
• Space: Based on the favorites list, look at the pots, raised beds, or garden space available for growing vegetables. Look at the space with an eye on directional exposure, light, and surroundings. An experienced vegetable gardener, Cathy grows a little bit of everything, including lots of tomatoes plus greens, peas, beans, and root vegetables. While she once had five acres, she now has a small garden space and works hard to maximize the potential by mapping out a plan for the garden space each year. She records progress notes to help in future seasons. In planning, also keep in mind that some crops, such as tomatoes, a member of the nightshade family, need to be rotated to a different area of the garden each season to limit pests and disease.

• Equipment: When choosing seeds for warm-season crops such as tomatoes, peppers, eggplant, and melons, remember that these need to be started indoors at home or in a greenhouse to be successful. A greenhouse is not required as many compact options are available to set up lights and heat mats on shelves indoors or in a garage.

• Skill level: For beginners, start on a smaller scale and add more vegetable varieties in future seasons. Also, consider doing some research and ask friends or neighbors with experience with vegetable gardens. Experienced vegetable gardeners rely on previous experience and notes taken during prior seasons on successful varieties and harvest results.

• Expense: Think about the vegetables that can be more expensive at the store or market and compare them to the cost of seeds and the season’s labor of love by the gardener. It can be easy to go crazy in the seed “candy store” so be mindful to purchase only the number of seeds to accommodate the space and objectives for the garden.

A greenhouse is not required to start seeds. Many compact options are available to set up lights and heat mats on shelves indoors or in a garage. Read more about building a DIY grow stand here > DIY Indoor Grow Stand  Photo © Cathy Markham, used with permission by Skagit County Master Gardeners

Research and understand seed options
After evaluating favorite vegetables, space, facilities, and skill level, research seed options. For starters, it helps to know how to read a seed description in a catalog website or seed packet. The gardener also needs to understand key terms, such as cultivar, heirloom, open-pollinated, hybrid, and resistance, as outlined in an article by Kym Pokorny and Nicole Sanchez of Oregon State University titled “Learn the Terms on Seed Packets to Make the Right Selection.”

When looking at seed options, consider the following key elements to consider for success in the maritime climate and relatively short growing season of northwest Washington:

• Days to maturity: It’s key to check how many days the crop needs to reach maturity. Cathy recommends choosing “early” varieties with 55 to 60 days to maturity to gain a successful crop. Seeds with 70 to 80 days to maturity can work; however, they may be more challenging. Seeds identified as reaching maturity at more than 80 days are rarely suited for northwest growing conditions.

• Understand the Zone: Check out the USDA Plant Hardiness Zone Map to confirm and learn more about the environment of the garden location.

• Consider Pacific Northwest-based seed producers: Several seed producers are located in Washington, Oregon, and British Columbia that may provide seed options designed for the region’s climate. Longtime Northwest seed producers include Ed Hume Seeds, Territorial Seed Company, and West Coast Seeds.

• Disease resistance: Look for seeds that will produce disease-resistant plants. The Pacific Northwest Vegetable Extension Group of Washington State University, Oregon State University, and University of Idaho has a great deal of information for gardeners at https://mtvernon.wsu.edu/path_team/
• Bolt tendency: When under stress, such as heat, some vegetables have a tendency to bolt, sending up flowers and producing seeds before the harvest. Check the seed description and look for “bolt resistant” or “slow bolting.”
• Space requirements: Matching up with the earlier evaluation of available pots, raised beds, and garden space, choose seeds for varieties sized to fit. Buy only what you will need for one or two years.
• Keep a record: Since 2010, Cathy has kept a notebook filled with clippings from seed catalogs or packets and adds notes about the season’s successes and failures to inform seed selection in future seasons.

Photo © Cathy Markham, used with permission by Skagit County Master Gardeners
A focus on tomatoes
As noted, Cathy has a special interest in raising tomatoes. This can be a joy and a challenge for Northwest gardeners based on the shorter growing season. The same can be said for peppers, eggplant, and melons, which all must be started in a greenhouse or indoor growing set up with heat and lights. Read more about building a DIY grow stand in blog article: https://skagitmg.org/indoor-grow-stand/

When reviewing tomato seeds, Cathy recommends giving special attention to the days to maturity, space needs, and available natural light. Dwarf, determinate varieties work well in pots as they are smaller and more compact. Also, think about the uses and flavors for tomatoes and select varieties to span salads to sauces.

In her search for seeds, Cathy focuses on growing different sizes of tomatoes in a “rainbow of colors” to enjoy fresh and in different types of preparations. She receives a variety of seed catalogs and orders favorites such as Italian Red Pear, an Italian heirloom (seeds available at Seeds of Italy, growitalian.com), and she is willing to try a new, emerging variety that may not be available locally.

Cathy’s small-scale garden space means her seed search must match her garden’s layers and vertical growth opportunities. Cathy uses a soil-blocking method to start seeds, planting a few more than needed to make sure she has enough, and uses an indoor shelf lighting and heat mat system in the garage to get her tomatoes started. Tiny tomatoes need daily monitoring for moisture, temperature, and light. As the small plants grow, Cathy occasionally will put the flats of fledgling tomatoes outside for a very brief time on warmer days to get a boost of sunshine.

Tomatoes: Determinate vs. Indeterminate
According to Washington State University Extension Fact Sheet #FS145E titled Vegetables: Growing Tomatoes in Home Gardens, “there are 7,500 varieties of tomatoes with differences in color, shape, growth habit, length to harvest, taste, and disease resistance. Tomatoes are classified as either determinate or indeterminate. Determinate varieties are bush-like, with all the tomatoes ripening about the same time. Indeterminate varieties are vine-like, with the tomatoes ripening throughout the growing season- until frost kills the plant.” Find a listing of Determinate vs. Indeterminate tomatoes on the Skagit Master Gardeners’ website > Determinate vs Indeterminate Tomatoes
Seeds selected, what’s next?
Learn more about germination, propagation, and the basics of growing vegetables. Resource publications include:  Propagating Plants from Seed by Pacific Northwest Extension Publishing and Home Vegetable Gardening in Washington by Washington State University Extension.

This is a non-inclusive list of seed purveyors to consider:

• Deep Harvest Farm deepharvestfarm.com/ Based on Whidbey Island.
• Ed Hume Seeds https://humeseeds.com/ Based in Puyallup, Washington.
• Johnny’s Selected Seeds Company johnnyseeds.com Based in central Maine.
• Renee’s Garden Seeds reneesgarden.com Based in California, sources and trials seeds from across the world.
• Territorial Seed Company https://territorialseed.com/ Based in central Oregon.
• West Coast Seeds https://www.westcoastseeds.com/collections/vegetable-seeds Based near Vancouver, British Columbia, Canada.

REFERENCES AND RESOURCES:

Bubel, N. (2018) The New Seed-Starters Handbook. Emmaus, PA. Rodale.

Daigre, S. and Garbee, J. (2015) Tomatomania!: A Fresh Approach to Celebrating Tomatoes in the Garden. New York, NY. St. Martin’s Griffin.

Fredericks, G., Cowan, J. and Daniels, C. (2014) Vegetables: Growing Tomatoes in Home Gardens. Washington State University Extension Fact Sheet #FS145E.

Kumar, M., Larsen, F. and Shekel, K. (2022) Propagating Plants from Seed. Pacific Northwest Extension Publishing. #PNW0170. Link here > 

LeHouiller, C. (2014). Epic Tomatoes: How to Select and Grow the Best Varieties of All Time. North Adams, MA. Storey.

Miles, C. (2013) Home Vegetable Gardening in Washington. Washington State University Extension Publication #EM057E. Link here > 

Pokorny, K. and Sanchez, N. (2021) Learn the Terms on Seed Packets to Make the Right Selection. Oregon State University Extension. Link here >

Ryan, K. (2015) Using Crop Rotation in Home Vegetable Gardens, Snohomish County Extension Fact Sheet. Link here>

Sanchez, N. (2019) The Basics of Selecting Garden Seeds. Oregon State University Extension. Link here >

United States Department of Agriculture, 2024, USDA Plant Hardiness Zone Map. Link here > 

Authors Kari Ranten and Cathy Markham

ABOUT THE AUTHORS:

Kari Ranten, MHA, is a retired journalist and healthcare communicator who became a certified Skagit County WSU Extension Master Gardener in 2024. Cathy Markham, a certified Skagit County WSU Extension Master Gardener since 2022, has a degree in food and nutrition from the University of Idaho and is a Registered Dietician.

What to do with your late-season bargain plant purchases?

Now that you’ve found those irresistible gems at marked-down prices how do you set them up for success in their new home?

By: Diana Wisen, Skagit County WSU Extension Master Gardener

It’s late summer, and you’ve found some plants on sale that are calling to you. Gardeners, like everyone else, love a good bargain. But when is a marked-down plant a good buy, or is something better left on the rack? Gardeners tend to be “nurturers” who hope that with plenty of TLC, they can nurture a plant back to full health. That may or may not be possible. You rarely can heal sick plants. Despite your efforts, diseased or heavily damaged plants are not a bargain at any price. Be forewarned! You could be bringing additional problems into your yard.

Nevertheless, you have given into temptation and brought home several marked-down plants. Now, what to do with them? First, take them out of your vehicle as soon as you get home, put them in a shady, cool place, and water them well. Allow the plants to drain. Once they are fully hydrated, do not leave them in standing water. Roots need air and will suffocate if left in standing water for several days. Check for baby slugs by sliding the plant out of its container. Also, check for healthy roots before putting it back in its container. Cut off dead stems, leaves, and flowers, but leave all healthy leaves so the plant can photosynthesize and grow.

Do you have a place in mind for each plant? Buying plants without a place to plant them can lead to a “Driveway Garden” with many potted plants sitting too long on the path to your house while waiting to be planted in your garden. This is not an unheard-of dilemma among gardening friends. However, let’s assume you have a place for your plant. Check for pests, disease, and damaged parts, including the roots, before planting. This should be done before you purchase the plant, but it’s better now than after it’s in the ground. Look for aphids, root maggots, beetle larvae, brown mushy (dead) roots, wounds on the stems, and diseased leaves. Sometimes, you can get away with cutting off diseased portions, but often the disease is in the vascular system and plants don’t “heal” like humans do. If you suspect disease, it is best to put the entire plant in the garbage can, not in your compost pile.

Check for healthy roots. Cut off dead stems, leaves, and flowers, but leave all healthy leaves so the plant can photosynthesize and grow.

Where to put your new plant
Read the plant tag to learn the conditions the plant needs to thrive. Can you provide the right kind of soil and drainage? What about the amount of sun or shade? Heat requirements? Wind protection? Are deer a problem? It is your job to give your plant what it needs. It cannot get up and move to a better site by itself.
How to plant
Planting is best done on a cool day or in the evening of a hot day. Water the plant and the planting spot ahead of time. Dig a hole the same depth as the plant’s root mass and three times as wide. Loosen the soil around the sides of the planting hole so the roots can grow outward. Place the plant in the hole and fill with the soil you took out. Water it in to settle the soil. Light mulching can help retain soil moisture and reduce weeding.

Sometimes marked-down plants are root-bound and some serious root pruning will be needed before planting. © Photographer: Ginny Bode

Cut off circling, broken, kinked or damaged roots. Very long roots may need to be shortened. © Photographer: Ginny Bode

For shrubs and trees, the root flare supporting the trunk should be clearly visible and not covered with soil or mulch. Take the plant out of the container and examine the root zone. Sometimes marked-down plants are root bound and some serious root pruning will be needed before planting. Cut off circling, broken, kinked, or damaged roots. Very long roots may need to be shortened. Do not cut off any of the canopy. Dig a wide, shallow hole, spread the roots straight out in all directions, replace the native soil, and water it in well. Do not stomp on the root zone. Make sure the base of the trunk is at the same level or a bit higher than the soil level. Mulch with arborist chips, keeping them an inch or two from the trunk.

Fertilizing and Care
Sometimes, you can tell by looking at the leaves if a plant is deficient in a nutrient. You need to know what is typical for this plant at this time of year. There are plenty of plants for which yellow or light green leaves are normal. Usually, fertilizing with a diluted nitrogen fertilizer at planting time is helpful. Just go easy on the fertilizer and avoid burning the roots. Too much fertilizer for shrubs, trees, and some perennials can cause excessive weak growth late in the season, which will be subject to winter damage. Soils here in the Pacific Northwest already have plenty of phosphorus. Adding phosphorous can kill the beneficial mycorrhizae. Do not add products such as vitamin B to the soil or spray leaves with a desiccant to prevent wilting. Despite manufacturers’ claims, they are not helpful.

A plant is considered established when its root system can take up sufficient water and nutrients for the plant to grow normally. Some shrubs and trees can take over a year, so remember to water them regularly, even if they are drought-tolerant. An arborist chip or homemade compost mulch will help keep the soil evenly moist and add slowly released nutrients. Most purchased composts are fine for a top dressing to retard water evaporation, but they have little or no nutrients left in them because they have been heated to very high temperatures to kill any possible pathogens. Many gardeners now use the “chop & drop” method of leaving plant debris on the soil to decompose naturally and add nutrients to the soil, becoming nature’s slow-release fertilizer.

PLANT YOUR PLANTS! Don’t let them languish on the driveway.
© Photographer: Ginny Bode
Container plantings require a different regimen.
Use a light soil mix, not garden soil for container planting. Add some of the compost mixed in well. A sufficiently sized drainage hole needs to be in the bottom of the pot. If slugs crawling in are a concern, put a coffee filter over the hole before filling. Do not put pieces of crockery or a layer of gravel over the hole in the container. New research shows this practice, which is frequently recommended in garden books, actually impedes drainage. Put the potting mix soil to the bottom of the pot so the roots will have plenty of room to grow. While urn-shaped containers are beautiful, they are more challenging to change out later on because the rim curves in and large established roots get caught under it and can be very difficult to dig out. Container plantings dry out much faster than in-ground plantings, especially as the roots grow and fill the pot. Frequent watering causes nutrients to be flushed out sooner so container plantings of annuals will need additional fertilizer during the growing season. A slow-release fertilizer can also be used. Always read the directions thoroughly before using any garden product.

Deadhead annuals to keep them blooming until frost. If they start making seeds that process signals the plants to stop producing additional flowers because they are nearing the end of their life cycle. Some containers can be brought indoors in the winter and continue to thrive if there is sufficient light. 

Now it is time to enjoy your new plants. Observe them daily and check to see if they need watering. Watch for plants starting to wilt and water them immediately. It’s OK to water plants in the middle of a hot day. Watering them will not cause leaf scorch but will keep your plants alive.

Some perennials may start to die back because they are at the end of their growing season and beginning to go dormant. Plant them properly, and they will come up next spring. Other perennials can be cut back, and they will produce a flush of new growth and perhaps lightly bloom again. Don’t forget to bait for slugs and snails, which can be treated the same. This time of year slugs are starting to lay their eggs, which look like masses of tiny white pearls in the moist soil. Slugs and snails live deep in the soil during winter. Read more about managing slugs and snails: https://skagitmg.org/managing_slugs_snails/

With the long growing season in the Skagit Valley, your new bargain plants can give you many months of pleasure. Enjoy the colors, textures, leaf shapes, plant forms, flowers and seeds, fragrances, and the overall beauty they add to your life and your neighborhood. It’s your garden. Plant what you love.

REFERENCES AND RESOURCES:

WSU Extension Master Gardener Training Course

Chalker-Scott, L. (2008) The Informed Gardener. Seattle, WA: University of Washington Press.

Chalker-Scott, L. (2009) Sustainable Landscapes and Gardens: Good Science-Practical Application. Yakima, WA: GFG Publishing, Inc.

Gilman, J. (2008) The Truth About Garden Remedies-What Works, What Doesn’t, and Why. Portland, OR: Timber Press.

Lowenfels, J. (2013) Teaming with Nutrients: The Organic Gardener’s Guide to Optimizing Plant Nutrition. Portland, OR: Timber Press.

Diana Wisen

ABOUT THE AUTHOR:
Diana Wisen has been a Skagit County WSU Extension Master Gardener since 1991 and is the coordinator of the Fuchsia Garden at the Discovery Garden on SR 536 in Mount Vernon.

Questions about home gardening or becoming a master gardener may be directed to Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the website: www.skagit.wsu.edu/mg

Mark your calendar for these upcoming master gardener events:

Skagit County Fair
Thursday ~ Sunday, August 8-11, 2024
Skagit County Fairgrounds
Building D
(map)
Visit our booth, see our displays, and talk with master gardeners about how to make your garden beautiful and productive.
Know & Grow Lecture Series
Season Extenders
Presented by Hallie Kintner
Tuesday, August 20, 2024 ~ 1 p.m.
Free Admission
NWREC Sakuma Auditorium
16650 State Route 536, Mount Vernon

A Second Act for Your Square 1-Gallon Pots at the Discovery Garden!

Bring your leftover square 1-gallon pots to the Discovery Garden (16650 State Route 536, Mount Vernon). The bin for recycling the square 1-gal pots is located in the parking lot, just north (to the right) of the main entrance.
We only need square 1-gallon pots like the ones pictured below (bottom right). The recycling bin will be available now through fall. Simply put your pots into the bin, and we take care of the rest!

Discover the Display Gardens Open House

Join us for this year’s Open House at the Discovery Garden,
the Salal Native Plant Garden, and the NW Fruit Garden
Saturday, June 29, 2024
10:00 a.m. ~ 2:00 p.m.
Free Admission & Parking

Visit 8 acres of gardens at one location in Skagit Valley

By Kay Torrance and Janine Wentworth
Skagit County WSU Extension Master Gardeners

Explore all three gardens and talk to the volunteers who maintain the gardens. Use your ‘Discovery Passport’ and map to lead you on a self-guided tour of educational displays and activities including:

• Container Gardening
• Growing Media for Container Gardening
• Drip Irrigation
• Plant Clinic
• Plant Sale

Also booths by:

• Skagit County Noxious Weeds
• Skagit County Natural Resources
• Skagit Conservation District

The Skagit Valley is home to three display gardens operated by volunteers as a learning resource for the public: the WSU Extension Master Gardener Discovery Garden, the Salal Native Plant Garden, and the NW Fruit Garden. The gardens are co-located on the grounds of Washington State University (WSU) Northwestern Washington Research and Extension Center (NWREC) in Mount Vernon, WA (directions).

Ask a Master Gardener
Skagit County WSU Extension Master Gardeners will be on-site to provide research-based solutions for your gardening challenges. Visit our Plant Clinic in the Pavilion for solutions to your plant problems or bring in a plant sample for identification. There will be a perennial plant sale. Bring your dull gardening tool to have it sharpened for free.

This year, master gardeners have crafted a special display on container gardening. Learn how to incorporate containers in your landscape or on your patio or balcony. Find out what you can grow and how to prepare the containers for success. There will also be information on planting media and using drip irrigation.

© Nancy Crowell Photography

© Kay Torrance
The Discovery Garden
Skagit County WSU Extension Master Gardener Discovery Garden features 30 themed garden rooms on 1.5 acres with ADA-accessible paths and educational displays. Designed to support Skagit home gardeners by promoting research-based gardening practices, master gardeners have created 30 garden rooms within the garden, featuring hundreds of plants chosen to flourish in Skagit Valley. Master gardeners will be on hand to show you their favorite plants.

The Discovery Garden began in 1994 when the Skagit County WSU Extension Master Gardeners had a vision for a garden that would demonstrate best practices for gardening in the Skagit area. After two years of planning, the garden’s first plantings of trees and installation of fences was completed in the fall of 1996, transforming a rural agricultural field into a public display garden. Check out the garden’s webpage and browse the 30 garden rooms to find inspiration for your garden.

Salal Native Plant Garden
The Salal Native Plant Garden is a half-acre oasis of native plants tucked behind the Discovery Garden. You can enter by walking through the Discovery Garden and following the paths to the south. Cool off in the shade and explore how you can incorporate low-maintenance natives into your home landscape. See how red osier dogwood, salal, cascara, vine maples, and others could look in your yard. Docents will be available for tours and to answer questions.

The Salal Native Plant Garden was created twenty-five years ago as a collaborative effort between volunteers of the Salal Chapter of the Washington Native Plant Society and the Washington State University Agriculture Extension Agency at Mount Vernon (WSU). 

NW Fruit Garden
The NW Fruit Garden (formerly WWFRF) is six-acres planted with fruit trees, berry bushes, and other fruit-bearing plants suited for our climate, along with espaliers and informative signage. Tour the Antique Apple Collection in the orchard’s inner oval or tour the entire orchard. Ask about pruning and thinning of fruit. Find out what fruit varieties are best for your needs. The garden includes many unusual plants, such as medlar, sea buckthorn, kiwi, Aronia, and haskaps.

The NW Fruit Garden is located on the west side of the Discovery Garden. The garden was initiated in 1991 to provide a resource for the public to view successful fruit varieties and cultural methods for our Pacific maritime climate. Whether you are choosing two or three fruit tree varieties for a small urban backyard or have a more extensive orchard for family or even farmers-market production, NW Fruit has information on variety selection and fruit culture for the Pacific Northwest.

Master gardeners are focusing on container gardening at this year’s Open House. Check out the options and growing media recipes. © Ginny Bode

Plant Clinic experts will be on hand to answer questions and diagnose your gardening issues. © Ginny Bode

If you can’t make the Open House, all three gardens are open and free to the public seven days a week from dawn to dusk. Visit the gardens throughout the year to view the seasonal changes. Signage in each garden identifies plants and makes for interesting and educational self-guided tours.

RESOURCES:

• Discover the Display Gardens website
• Skagit County WSU Extension Master Gardener website
• Salal Native Plant Garden website
• NW Fruit (Western Washington Fruit Research Foundation website

ABOUT THE AUTHORS :

Kay Torrance and Janine Wentworth are Skagit County WSU Extension Master Gardeners and part of the Planning Committee for the annual Open House.

Questions about home gardening or becoming a master gardener may be directed to: Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the website: www.skagit.wsu.edu/mg

Mark your calendar for these upcoming master gardener events:

Skagit County Fair
Thursday ~ Sunday, August 8-11, 2024
Skagit County Fairgrounds
Building D
(map)
Visit our booth, see our displays, and talk with master gardeners about how to make your garden beautiful and productive.
Know & Grow Lecture Series
Season Extenders
Presented by Hallie Kintner
Tuesday, August 20, 2024 ~ 1 p.m.
Free Admission
NWREC Sakuma Auditorium
16650 State Route 536, Mount Vernon

A Second Act for Your Square 1-Gallon Pots at the Discovery Garden!

Bring your leftover square 1-gallon pots to the Discovery Garden (16650 State Route 536, Mount Vernon). The bin for recycling the square 1-gal pots is located in the parking lot, just north (to the right) of the main entrance.
We only need square 1-gallon pots like the ones pictured below (bottom right). The recycling bin will be available now through fall. Simply put your pots into the bin, and we take care of the rest!

Hypertufa Troughs Serve as Lowland Homes for Native Alpine Plants

Grow these tiny gems seen on an alpine hike

By: Sonja Nelson, Skagit County WSU Extension Master Gardener

Nestled low to the ground among the peaks of the North Cascade Mountains are tiny alpine plants that delight hikers as they stroll the high country of Skagit and Whatcom Counties. If these hikers are also gardeners, it is tempting to dig a few of these gems to take home and plant in their home garden. Digging and removing plants is, of course, prohibited on public lands, including national parks, forests, and recreational areas. Moreover, the plants most likely would die when snatched out of their high-altitude environment and planted in the soils found in the lowlands of our ecoregion.

However, alpine gardening enthusiasts have found a solution to recreate the beauty they see in the alpine regions of the North Cascades. Using containers created to grow plants away from their native environment and plants purchased from nurseries specializing in alpine plants, gardeners can successfully grow these tiny gems seen on an alpine hike.

The containers, called “hypertufa troughs,” are constructed to provide the specific requirements alpine plants and succulents need to thrive. They also blend nicely into a garden or can be placed on a deck or patio.

Hypertufa trough planted with mountain heathers native to the North Cascades. The trough is placed on a deck in Bayview in Skagit County. Photo © Sonja Nelson

Snow covering the mountain heathers trough, pictured in Photo 1 (to the left), acts as insulation just as it does for these plants in their native home in the North Cascades. Photo © Sonja Nelson

Hypertufa troughs originated from the naturally occurring tufa rock, a type of limestone formed when carbonate minerals precipitate out of water and build up around organic matter, eventually decomposing, leaving a porous rock. English farmers of the 1800s chiseled feeding troughs for their animals out of this rock. Years later, creative gardeners adopted these old containers, covered in moss and worn by decades of exposure to the elements, as decorative planters. A few of these sought-after antique troughs are still found in Europe but are often too heavy and expensive to transport across the Atlantic. (1)

Since tufa rock was not readily found and available in the US, gardeners in the 1930s-1940s began to make tufa-like troughs using a mix of ingredients with Portland cement. They called them “hypertufa.” (2)

Growing small alpine plants in hypertufa troughs has many advantages. The trough materials serve as insulation against extreme hot and cold temperatures that can occur in our ecoregion. The troughs also drain well, so standing water is never a problem, and the roots of alpine plants grow into the porous hypertufa and tend to thrive.

In addition, the Portland cement in the hypertufa mix slowly releases some calcium and magnesium that plants need. And, because the trough is relatively lightweight, they can be moved from place to place in the garden for the best exposure through the seasons. (2)

Ecoregions
Growing alpine plants in hypertufa troughs gives gardeners the pleasure of seeing them close to home in their gardens and protects them from the possible ravages of warm summers in their native locations.

Skagit Valley is located in the Puget Trough ecoregion, with mild, wet winters, and warm, dry summers. Here, precipitation averages 40 inches per year, with a mean January temperature of 39° F and a mean July temperature of 65°F. This climate differs from the climate of the North Cascades ecoregion, where many of our Washington native alpines for our hypertufa troughs grow in the wild. High elevations in the alpine regions are often covered with snow for many months. (3) The North Cascades Highway (State Route 20) traverses this ecoregion’s subalpine and alpine sections.

The Plants
The choice of North Cascade alpine plants for troughs is considerable. To get started, as an example among alpine plants, choose from the mountain heathers, the saxifrages, and the gentians.

White mountain heather (Cassiope mertensia) near Mt. Shuksan in the North Cascades. © Sonja Nelson

Mountain Heathers
The common name “heather” can refer to many different highland species throughout the world. North Cascade heathers are called “mountain heathers” and include the genera Cassiope and Phyllodoce. Common names include white mountain heather, Alaskan mountain heather, pink mountain heather, and yellow mountain heather. (6)
Saxifrages
Members of the genus Saxifraga are widespread in the North Cascades, many of which grow in the subalpine and alpine regions. Examples seen by the author are Tolmie’s saxifrage (Saxifraga tolmiei) at Chain Lakes, Alaska saxifrage (Saxifraga ferruginea) at Twin Lakes, and western saxifrage (Saxifraga occidentale) on Chowder Ridge (Pojar and Mackinnon1994).

Saxifrage at Bagley Lakes in the North Cascades. © Sonja Nelson

Broad-petalled gentian (Gentiana platypetala) at Cutthroat Pass in the North Cascades. © Sonja Nelson

Gentians
Members of the genus Gentiana are also widespread in the North Cascades. Four gentian species are native to the North Cascades: king gentian (Gentiana septum), broad-petalled gentian (Gentiana platypetala), swamp gentian (Gentiana douglasiana), and alpine bog swertia (Swertia perennis). (6)

Although hypertufa troughs are highly suitable for growing alpines at low elevations, many small native plants and succulents also find the troughs an amenable environment for growth and a refuge from fluctuating temperatures.

Growing Mix
The soil mix used in the troughs cannot be the same as the soil in your garden. Alpines especially need good drainage, which means water seeps through the medium quickly and does not pool around the plant crowns.

A basic trough medium recipe is 2/3 to 3/4 by volume potting mix with either peat or coconut coir and 1/3 to 1/4 by volume coarse perlite. Add fertilizer if the soil mix does not include it. (2)

The extensive Trough Courtyard at the UBC Botanical Garden in Vancouver, BC features an extensive collection of alpine rock plants. © Ginny Bode

This tiny Brassicaceae is tucked between rocks in a trough garden at the UBC Botanical Garden. © Ginny Bode
Making Hypertufa
Recipe mixes for hypertufa can be found on the Internet. The recipe below is from Rosemary Read, Editor of The Social Gardener for the Whatcom Horticultural Society.
Lightweight Frost-proof Troughs “Tufa”
by Rosemary Read, Editor, The Social Gardener

Materials Needed (parts by bulk):

• 1 part Portland cement
• 1 ½ parts fine peat (screened)
• 1 ½ parts horticultural vermiculite and/or perlite
• 2 cardboard boxes (which, when fitted one inside the other, leave a gap of approx. 2 in. between the sides.)
• 2-3 wood dowels (approx. 2 in. long)
• Chicken wire (or metal strips) for reinforcement

Peat Moss and Sustainability

Increasingly, master gardeners are looking towards sustainable materials and encouraging gardeners to use a peat moss substitute whenever possible. Coconut coir is a sustainable product, and can be used instead of peat moss at a ratio 1.5:1 of the coconut coir and cement to water and perlite. However, it does not decompose as quickly as peat moss, which leaves pits and crevices and resembles true tufa rock. The full recipe and directions for using a peat substitute can be found here > 

Download the full report debunking the myth of the sustainability of peat bogs by Linda Chalker-Scott, PhD., WSU Extension Urban Horticulturist and Associate Professor.
Download here>
Steps to Making a Hypertufa Pot
Mix the dry ingredients and add water to make a thick, creamy consistency that can be poured. Mix in an old wheelbarrow, bucket, or container that can be moved and washed out when the project is complete.

1) Set up the outer mold cardboard box where you can move around it freely and where it may be left to harden. It is best to cover surfaces with plastic.

2) Pour mixture into the floor of the outer mold (2″ or more).

3) Press the wooden dowels into the mixture. In addition to making drainage holes, the dowels will support the inner box.

4) Place the inner mold on top of the dowel plugs.

5) Place in chicken wire (along sides and corners).

6) Pour in the mixture until it reaches the top.

7) Leave 24 hours. Remove the outer mold (peel off).

8) Rough sides to make it look “old” (chisel).

9) Leave the inner mold longer to harden.

10) Leave trough a week or more to harden before knocking out the plugs.

11) Leave the trough for 2 weeks to “cure” by soaking it in water, which is changed every 2-3 days.

_______ – _______

Safety Warning: Concrete contains chemicals that can cause skin irritation and lung damage. Read the warning labels on the material purchased. When working with concrete, always wear gloves, a facemask, safety glasses, and old clothing. Set up your work area outside, away from breezes, children, and pets.

_______ – _______

Outer box: 16 ½” x 13 ¼” x 8″
Inner box: 13″ x 9 ¼” x 6-8″
Trough Size (inside): 13″ x 9 ¼” x 5 ½”

REFERENCES AND RESOURCES:

1. Carpenter, J. How to Make a Hypertufa Garden Trough. Retrieved from: This Old House.com

2. Chips, L. (2018). Hypertufa Containers. Portland, OR, Timber Press

3. Ecoregions in Washington, Landscape America, (http://www.landscope.org/washington/natural_geography/ecoregions/).Read, R., Personal Communication, (May, 2024). Lightweight Frost-proof Troughs “Tufa” The Social Gardener, Whatcom Horticultural Society, Bellingham, Washington.

4. Reed, W. High and Dry for a NW Icon. (2023, Fall). Washington State Magazine
Retrieved from: https://magazine.wsu.edu/2023/07/31/high-and-dry-for-a-nw-icon/

5. Pojar, J., MacKinnon, A. (1994). Plants of the Pacific Northwest Coast: Washington, Oregon, British Columbia and Alaska. Tukwilla, WA, Lone Pine Publishing.

Sonja Nelson

ABOUT THE AUTHOR:

Sonja Nelson is a Skagit County WSU Extension Master Gardener, Class of 2009.

Questions about home gardening or becoming a master gardener may be directed to:  Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the website: www.skagit.wsu.edu/mg

Know & Grow
Gardening for Fragrance
Presented by Diana Wisen
Free
Tuesday, June 18 ~  1 p.m.
NWREC Sakuma Auditorium
16650 State Route 536, Mount Vernon

Visit the annual Open House at the Display Gardens:

Saturday, June 29
10 a.m. to 2 p.m.
Free Admission & Parking
Discovery Garden
16650 State Route 536, Mount Vernon
Learn More >

A Second Act for Your Square 1-Gallon Pots at the Discovery Garden!

Bring your leftover square 1-gallon pots to the Discovery Garden (16650 State Route 536, Mount Vernon). The bin for recycling the square 1-gal pots is located in the parking lot, just north (to the right) of the main entrance.
We only need square 1-gallon pots like the ones pictured below (bottom right). The recycling bin will be available now through fall. Simply put your pots into the bin, and we take care of the rest!

What’s in Your Bag of Potting Soil?

Not All Potting Soils Are Created Equal

By: Bruce Lindsay, Skagit County WSU Extension Master Gardener

As spring advances, gardening stores offer a multitude of soil mix choices. Selection can seem daunting, so we asked fellow master gardener and soils expert Bruce Lindsay to take us on a deep dive into what potting soils are made of and how to amend commercially bagged potting soils to ensure the best success in our container and raised bed plantings.
                                                             — Ask a Master Gardener Editors
What exactly is in a bag of commercially produced potting soil?
The first step is learning the basics of soil. All soil primarily consists of sand, silt, and clay mineral particles. Sand is visible to the naked eye, ranging from 0.05 to 2mm in diameter, and is gritty to the touch. Silt is not visible to the naked eye and looks and feels like flour when it is dry. When it is wet, it feels like damp flour dough. Silt ranges from 0.002 to 0.05mm in diameter. Clay is the size of bacteria, less than 0.002mm, and has colloidal properties as the result of its net negative charge due to its crystal structure. In a natural setting, soils have pores made by plant roots and insects, which are essential for drainage and allowing air to enter the soil for roots to breathe. The size of the pores is also important for water movement and the soil’s ability to retain water.

In contrast to well-balanced mineral soil, purchased potting soil typically has very few of these properties and has several problems. But take heart, armed with scientific knowledge, gardeners can remedy many of these deficiencies.

The vast majority of bagged “potting soil” consists of ground wood and bark produced from recycled forestry products (RFP). Commercially bagged soils are available in multiple mixtures containing RFP, peat moss, and other additives. © Photo: Adobe Stock

For seed starting and plant repotting, master gardeners use a moist, good quality potting soil mixed with perlite. © Skagit County WSU Extension Master Gardeners

The vast majority of bagged “potting soil” (technically called a potting “medium” even though the label calls it “soil”) consists of ground wood and bark produced from recycled forestry products (RFP). Various commercially bagged soils are available, from coarse bark to multiple mixtures of RFP, peat moss, and other additives. In contrast, mineral soil products combine mineral particles of various sizes with some added compost. The potential hazard with some commercially bagged soils is the possible presence of weeds such as horsetail (Equisetum) and the potential presence of herbicides coming from landscaping sprayed with herbicide or hay fed to animals that has been sprayed and persists through a composted state and cause damage when used as potting soil.

Dealing with Nitrogen Deficiencies 
Recycled forest products are commercially sold in large bark chunks as mulch and finer-grained material as potting soil. These products come with inherent problems that gardeners can solve with amendments. The first issue that must be addressed is the carbon-nitrogen ratio (C/N). The ground-up wood materials in these bagged soil products are often almost pure cellulose, and bacteria (microorganisms) love to eat it. When bacteria eat stuff, they make many more bacteria and require more nitrogen as they reproduce, which results in nitrogen deficiency, leading to poor plant growth.

Older leaves turning yellow while the young leaves are green is often a sign of nitrogen deficiency. Severe nitrogen deficiency results in a severe lack of growth and stunted plants. One must take care when adding nitrogen; too much will promote rapid growth and excessive foliage. It can be a tricky balance, but fertilizer with some phosphorous and potassium is best. Some fertilizers also contain micronutrients, which can be beneficial. Use a significantly diluted solution (1 TBSP per gal.) of soluble fertilizer and frequently monitor the plants to see how they are doing.

Perlite is a volcanic glass, which, when subjected to heat and pressure, it changes, puffs up like popcorn, and forms many tiny pores that can hold water.

It is surprising how much wood is included in a bag of potting soil. © Skagit County WSU Extension Master Gardeners

Since the recycled forest products used in commercially sold products are very porous, much of the fertilizer will drain through the pot in one application. To solve this problem, use well-composted materials containing organic matter or humus for effective nutrient retention. Well-composted materials should not include a lot of materials like straw and sawdust. Bacteria love sugars and cellulose, as in the “greens” of composting terminology, but bacteria have a hard time breaking down the “browns,” which contain lignin. If there were only sugars and cellulose in composting, bacteria would consume everything, and nothing would be left. The compost “browns” in soils contain materials high in lignin, resulting in “humus” as the ultimate end product of composting. One benefit of humus is that it is very good at holding water. Another significant advantage of adding well-composted materials to a soil mixture is that it will also add beneficial bacteria and fungi that are essential for many processes, just as they are in healthy mineral soils. Another benefit is that humus has a net negative charge that can hold onto cations such as potassium, calcium, and magnesium, giving the soil cation exchange capacity essential to plant growth.

The Importance of Cation Exchange Capacity (CEC)
Balanced mineral soils contain clay particles with a negative charge that hold onto the cations. Bagged potting soils containing a heavy ratio of recycled forest products do not have any clay, so the cations get leached out. To amend this problem, add well-composted materials to the RFPs. Hydrogen ions are cations that stick to negatively charged humus particles like little magnets. When fertilizers are applied, the calcium, magnesium, and potassium displace the hydrogen cations and become stuck to the humus particles. Plant roots come along, exude acids, and displace the nutritional cations, which are absorbed by the root and go up into the plant.
Wikipedia defines CEC as:
Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces.[1] Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with other positively charged particles in the surrounding soil water.[2] This is one of the ways that solid materials in soil alter the chemistry of the soil. CEC affects many aspects of soil chemistry, and is used as a measure of soil fertility, as it indicates the capacity of the soil to retain several nutrients (e.g. K⁺, NH₄⁺, Ca²⁺) in plant-available form. It also indicates the capacity to retain pollutant cations (e.g. Pb²⁺)

Many garden centers now carry a soil amendment called humic acid (or related substances, humin and fulvic acid). These are still the subject of much scientific debate. These compounds are created by alkaline extraction and are not naturally present in soil. While humic substances may have some positive effects on root growth, home gardeners are best advised to focus on the longer-term building of soil organic matter through carbon-rich amendments such as compost (or cover crops for garden beds), etc.

The Soil‘s Capacity to Hold Water
It is essential to slow the water down so plants have the opportunity to absorb it. Fortunately, most ornamental plants and vegetables prefer well-drained soil and do not like being in standing water for very long. In contrast, due to their fibrous material, most hanging baskets need watering once a day.

Add popped perlite and/or vermiculite to the mix to increase water retention. Perlite is a volcanic glass, which, when subjected to heat and pressure, it changes, puffs up like popcorn, and forms many tiny pores that can hold water. Perlite is the little white balls often added to soil mixes.

Vermiculate is a naturally occurring mineral that is also heated to create the golden-brown cube-like material we see added to soils. Vermiculite draws in and holds water like tiny sponges throughout the soil. You can also use coconut coir as a moisture-holding material, but soak it thoroughly before adding it to a mixture.

The water-holding capacity of pelletized wool is an exciting new material being tested. Pelletized wool is composed of the short wool fibers from the underside of sheep where the wool is also much dirtier and has plant fibers embedded; it is not suitable for processing into fabrics. This material has been a waste product of the wool industry. Recently, however, research has shown that this material is a viable amendment to soil that improves the water-holding capacity of soil and provides some slow-release nutrients. Already sold commercially this material is pelletized for ease of mixing into soil and is a productive, sustainable use for a by-product typically diverted to a landfill.

The Addition of Slow-Release Fertilizers
Bagged potting soil products often offer slow-release fertilizer additives. Beware of those using tiny plastic beads to store the nutrients. Our soils do not need synthetic materials left behind. Instead, some products use fertilizers with a mineral coating, such as limestone or gypsum, that slowly dissolves, releases the inner contents, and does not leave behind plastic residue.

Other slow-release products consist of blood, bone, and feather meal, which are by-products of meat processing. The drawback of these materials is the smell they generate. They are acceptable when used in a field but not welcome on a patio in a hanging basket. Likewise, fish emulsion is a fairly slow-release fertilizer but also has a considerable odor problem. While it is an organic fertilizer, one must consider the odor it causes and that it is a by-product of overfishing of oceans.

Adding ground limestone to the mix may be a good idea because the recycled wood product material tends to be on the acidic side. The limestone will add some alkalinity. Dolomitic limestone is even better, as it contains magnesium and will be a slow-release source of calcium and magnesium. Be sure to mix it well with the potting soil. About a cup per cubic yard should be enough. If you have access to a pH tester, use it! The soil pH indicates the availability of essential nutrients needed for plant growth. Ideally, potting soil should have a pH of about 6.5. It is important to test the pH of your soil mix before adding an amendment to raise or lower the pH.

Basic food waste from the farming, grocery, and restaurant industries is a readily available slow-release fertilizer. It is stunning that forty percent of our food production goes into landfills. An alternative is an organic liquid product made from fermented food and vegetable waste. It doesn’t stink and smells good, somewhat like soy sauce. With landfills overflowing, diverting food waste into soil improvement and garden production is one way to improve our environment.

Some people think replacing their potting soil with fresh material each year is necessary. This is only the case if there are disease issues. For instance, potting mix used for tomatoes or potatoes should not be used again for those plants because they are both susceptible to soil borne diseases. After a season of growing and watering, all the nutrients have leached out, but you can easily replace the nutrients by using the dilute fertilizer solution mentioned above. If the soluble fertilizers are too concentrated and the plants are not utilizing them, they may accumulate as salts. As time passes, some of the RFP in the potting soil will get eaten by bacteria, and the volume will decrease. In this case, add new potting soil with the amendments and mix it well with the original soil, spreading the nutrients around.

These recommendations apply to soil used in containers, raised beds and hanging baskets. It also applies to starting seeds in trays, but the seed starting soil material should be very fine to ensure good contact between the seed and the moist growth medium. When starting seeds, the soil should also drain fast enough so a fungal damp-off situation does not develop. Sphagnum peat moss tends to float to the top when watered and begins to clog pores, making it difficult to get moisture down to the bottom of the cell. Sprinkling fine vermiculite on the very top of each cell can help prevent these problems.

While forestry products recycled as commercial potting soil have drawbacks, amending these insufficiencies is an easy process. It is much better to use RFP products than to burn, bury, or dump them into the overflowing waste stream. Armed with awareness of the limitations of modern “potting soil” and knowing some remedies, gardeners can buy these products feeling confident with scientific knowledge.

REFERENCES AND RESOURCES:

Beck, L. (2023). ‘Waste Wool‘ is a Burden for Farmers. What if it Could be a Solution Instead? Retrieved from https://modernfarmer.com/2023/11/waste-wool-solution/

Brady N., Weil, R. (2017). The Nature and Properties of Soils. London, UK. Pearson Education (15^th ed.)

Lehman, J., Keber, M. (2015). The Contentious Nature of Soil Organic Matter. Nature volume 528, pp 60-68.  https://www.nature.com/articles/nature16069

ABOUT THE AUTHOR :

Bruce Lindsay became a Skagit County WSU Extension Master Gardener in 2015. With an MS degree in geology and an MS degree in soil, he has mapped soils in Nevada, Arizona, California, and Washington.

Questions about home gardening or becoming a Master Gardener may be directed to: Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the website: www.skagit.wsu.edu/mg

Upcoming Skagit Master Gardener Foundation Events:

Know & Grow:
Growing Roses in Skagit County – Free
Presented by Virgene Link-New
April 16, 1 p.m. 
NWREC Sakuma Auditorium
(16650 State Route 536, Mount Vernon)

Free Admission & Parking
May 11, 8 a.m. to 2 p.m.
Skagit County Fairgrounds
Learn More >

A Second Act for Your Square 1-Gallon Pots at the Discovery Garden!

Bring your leftover square 1-gallon pots to the Discovery Garden (16650 State Route 536, Mount Vernon). The bin for recycling the square 1-gal pots is located in the parking lot, just north (to the right) of the main entrance.
We only need square 1-gallon pots like the ones pictured below (bottom right). The recycling bin will be available now through fall. Simply put your pots into the bin, and we take care of the rest!

Gardening for All Ages and Abilities

Practical tips and ideas for adapting the garden through life’s transitions

By: Ginny Bode with Madelyn Case and Anita Reetz, Skagit County WSU Extension Master Gardeners

Gardeners know spending time in the garden feeds the soul. But sometimes, as life changes, we face the need to adapt how we garden so it is possible for ourselves or those we love to continue cultivating wellbeing through gardening.

For some, physical limitations present lifelong challenges; for others, aging begins to interfere with the bending, kneeling, and digging associated with gardening. There are many reasons to take heart and continue to enjoy gardening by implementing some of these adaptive methods.

In her book Gardening for a Lifetime, Sidney Eddison sums up the reason for adapting when she says, “We are all doing exactly the same thing-trying to hang on to something we love.” Her book is loaded with practical ideas for reducing and removing barriers that hinder and continue the joy of growing plants through life’s transitions.

Reducing the size and work of a garden is the first step, followed by making it easier, more accessible, and user-friendly. A vegetable garden the size you’ve always had, and probably shared with others, can be resized to reduce both the work of maintaining and the work of harvesting. Choose to grow your top favorites, looking for plants that require less maintenance.

Eddison writes about requiring a “standard of good behavior” for perennials. Her measure includes observing a perennial’s health, fortitude, and ability to withstand the extremes of summer and winter. They must be “well-behaved” and not invite pests. As plants age out, replace them with sizes and varieties that are easier to maintain. And, because climbing ladders is problematic as we age, choose low-profile trees and shrubs that are easier to reach for pruning and maintenance.

Pay Attention to Walkways
Every garden needs to be accessible and safe. Falls are problematic and can limit the ability to garden even more. Remove any places that may cause one to stumble. Eliminate a dip in a walking path and poor transitions between surfaces. Smooth pathways such as pavers, rather than woodchips or gravel, ensure ease for every gardener, particularly those who need the aid of a cane, walker, or wheelchair.

Herbs and lettuces can easily be grown in containers making it easy to gather when preparing a meal.

If the space doesn’t allow a large footprint, grow vertically with trellises in pots. Tomatoes are a beautiful addition, and can drive grown vertically with good airflow.
Be Amazed by What Can Be Grown in Containers
Life can throw us a curve, and home may change from acreage or a city lot with a garden to an apartment. Don’t let it rob the joy of gardening. When faced with gardening on a patio, containers can provide an excellent way to get a dirt fix. Most home gardeners are familiar with growing flowers in pots and containers. Many also successfully grow a wide range of vegetables, including tomatoes, beans, and kitchen herbs in pots. Depending on the space and container size, some folks even grow potatoes! The Vegetable Gardener’s Container Bible by Edward Smith provides advice for growing an abundant vegetable garden on your patio or balcony. Smith’s book is a stalwart in gardeners’ libraries because it is packed with information covering sun exposure, pot size, soil choices, and which varieties do best in containers.

A narrow bench fitted to the edge of a raised bed allows for tending without kneeling.

Raised beds are also an excellent solution to making the garden user-friendly, making it possible to get your hands in the dirt without bending or kneeling. By keeping the beds narrow, 4′ or less, every inch of the garden is reachable from a standing or wheelchair position. It is incredible how much can be grown in a raised bed. With the popularity of raised beds, kits that only require simple assembly are available, or you can use the plans referenced later in this article.

Master gardener and adaptive gardening consultant Toni Gattone shares many adaptive gardening ideas in her book The Lifelong Gardener. Faced with chronic back pain, she searched for ways to adapt her northern California garden. She collected considerable wisdom about assessing limitations and finding joy in the changes. In the book, Toni profiles several gardeners faced with specific challenges and how they solved them with intentional choices and tools.

Gattone has a chapter about tools available for gardeners who face physical challenges. Scooters, carts, and ergonomically designed tools reduce some of the problems caused by aging joints. Long-handled hoes and weeders can make it much easier to garden from a bench.

Share a Gardening Space with a Friend or Join a Community Garden
Another way to garden without a home garden is to share a space. Many communities have garden spaces for people who need a place to garden. Whether in a community garden or sharing space in a friend’s garden, both offer the additional benefit of social interaction and shared knowledge.

The Enabling Garden features an abundance of garden possibilities for making it easier to garden for all ages and abilities © Nancy Crowell Photography
See the Possibilities in Action
As spring turns to summer, you will find inspiration for adaptive gardening techniques in the Skagit County WSU Extension Master Gardener’s Discovery Garden on Memorial Highway (SR 536), west of Mount Vernon. Within the one-and-a-half-acre garden, local master gardeners have created an Enabling Garden, showcasing possibilities for people of all ages with limited physical abilities.

The Enabling Garden’s features include:

• Smooth ground surfaces
• Raised beds
• Resting places
• A display of adaptive gardening tools
• A selection of plants chosen for their sensory attributes or space

Many tools are available to help ease physical challenges. Long-handled hoes and weeders can make it much easier to garden from a bench.
© Ginny Bode

White stones delineate areas for the visually impaired in this raised bed in the Enabling Garden

Tripartite garden plants; wheelchair accessible.

Rather than wood chips or gravel, pavers allow visitors with walkers or wheelchairs to move about easily. The raised bed design (8-foot x 4-foot x 1-3-foot) permits the gardener to reach every inch of each bed, standing or from a wheelchair. You’ll find more information about raised beds along with plans at https://skagitmg.org/raised-beds-2023/.

One raised bed features a sitting ledge to offer a rest from work. Another bed is designed for the visually impaired and features curved streams of small white rocks separating plant clusters and plants with different textures to touch and feel. A third raised bed is divided into three parts with cutouts to push in a walker or wheelchair.

A fourth raised bed features a vertical lattice panel in the center, supporting various runner beans and clematis. The panel, located in the middle, permits tending from both sides. Square foot gardening techniques are displayed in another raised bed where 24 one-foot squares, laid out with twine, show the variety and abundance of small vegetables, herbs, and flowers that one raised bed produces.

The coordinators of the Enabling Garden choose plants for their ability to satisfy the senses of smell, touch, hearing, and taste. Kids visiting this garden say, “It’s fun to feel” the wooly lambs’ ear (Stachys byzantina), spiky lemon thyme (Thymus citriodorus), saxifrage, trailing English ivy (Hedera helix), and soft moss that flourish in the bed designed for the visually impaired. Fragrant plants throughout the garden include lilies, mint, sage, violets, and sweet peas. Herbs like lavender, rosemary, and lemon verbena can energize the gardener. You will find plants included for their sounds, too! Balloon flowers (Platycodon grandiflorus), bamboo, Chinese lantern plants (Physalis alkekengi), and honesty (Lunaria annua) provide interesting and pleasant sounds.

Within the Enabling Garden, you’ll also find a display picturing enabling tools, showing the tool and explaining how it helps gardeners use less energy and work more effectively.

These tips only touch on surface ideas to make it possible to experience the rewards of gardening no matter what physical limitations a gardener faces. The resources below dig deeper into the possibilities for gardening at any age or ability.

REFERENCES AND RESOURCES:

Eddison, S. 2010. Gardening for a Lifetime: How to Garden Wiser as You Grow Older. Timber Press Portland, OR.

Smith, E. 2011. The Vegetable Gardener’s Container Bible. Storey Publishing, North Adams, MA.

Bartholomew, M. 2018. All New Square Foot Gardening: Grow More in Less Space! Cool Springs Press, Franklin, TN.

Gattone, T. 2019. The Lifelong Gardener: Garden with Ease and Joy at Any Age. Timber Press, Portland, OR.

Ginny Bode

Anita Reetz

Madelyn Case

ABOUT THE AUTHORS :

Ginny Bode, Anita Reetz, and Madelyn Case are Skagit County WSU Extension Master Gardeners. Anita and Madelyn are the coordinators of the Enabling Garden at the Discovery Garden on SR 536 west of Mount Vernon. https://skagitmg.org/home/discovery-garden/

Questions about home gardening or becoming a Master Gardener may be directed to: Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the website: www.skagit.wsu.edu/mg