The Evergreen Thumb

Washington has temperate rainforest, sagebrush steppe, and alpine meadows within the same state, so gardening advice that works in one region may not work in another. This episode explains how Level III ecoregions, a framework developed by the EPA, can help you understand the conditions in your own garden.

We start with what a Level III ecoregion is and how it differs from a USDA hardiness zone. Then we cover eight Washington regions:

• Coast Range
• Puget Lowland
• Cascades
• North Cascades
• Eastern Cascades Slopes and Foothills
• Columbia Plateau
• Blue Mountains
• Northern Rockies

For each region, we look at the climate, the soils, the native plants that grow there, and what those conditions mean for your garden.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

In this episode of The Evergreen Thumb, Erin Hoover talks with Tim Kohlhoff about the role trees play in creating healthier, more livable communities. They explore why urban tree canopies matter, the challenges communities face in protecting them, and how thoughtful tree planting can help shape the future of our neighborhoods.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

In this episode of The Evergreen Thumb, Erin Hoover covers everything you need to know about growing garlic in Washington state. She explains the difference between hardneck and softneck garlic, shares her own growing experience, and touches on elephant garlic as well.

Erin walks through site selection, sourcing seed garlic, regional planting timing, spacing methods, and mulching for winter protection. She covers scape removal in early summer and when to stop watering before harvest, then closes with guidance on curing garlic for maximum storage life and an overview of common garlic pests and diseases, including prevention tips like crop rotation and separating garlic from onions.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

What does it take to protect important crops from harmful plant pathogens? In this episode of The Evergreen Thumb, we explore the work of the Clean Plant Center Northwest at Washington State University with its director, Sudarsana "Sud" Poojari.

Sud explains what clean plant material means, why it matters to U.S. agriculture, and how plant material moves through testing and treatment before being released as clean foundation material. We also explore how that foundation material is used by commercial growers and nurseries to help produce healthy fruit trees, grapevines, and hop plants.

In this episode:

• The mission and role of the Clean Plant Center Northwest
• What "clean plant material" means and why it matters
• The journey of plant material through testing and treatment
• How clean foundation material supports fruit trees, grapes, and hops
• How commercial growers and nurseries use clean plant material
• What CPCNW's work means for home gardeners
• The future of clean plant programs

Resources mentioned in this episode, along with a full transcript, can be found on our website.

Fall may feel like the end of the gardening season, but for many spring-flowering plants, it's just the beginning.

In this episode of The Evergreen Thumb, Erin explores fall planting in Washington, with a focus on spring-flowering bulbs and other geophytes. We'll look at why fall is the right time to plant many of these plants, how soil temperature affects planting timing, and what Washington gardeners should consider when deciding when to get their bulbs in the ground.

We'll talk about familiar garden favorites such as daffodils, tulips, and hyacinths, along with some less familiar native geophytes, including camas and fawn lilies for seasonal interest and to support regional biodiversity.

Cover crops can protect and improve garden soil during the time of year when our gardens are resting. In this episode, Erin talks with Twinflower Wilkie, a WSU Extension Master Gardener in Ferry County, about how cover crops help retain moisture, protect soil from erosion, cycle nutrients, and build healthier soil.

Twinflower also shares why cover crops can benefit pollinators and other beneficial wildlife, and why allowing your garden to go a little wild can be good for the garden and the creatures that depend on it. They discuss choosing and using cover crops in the home garden and simple ways gardeners can get started.

For gardeners in Washington's dry eastern climate and beyond, cover crops offer a practical way to keep soil protected and productive while creating a more welcoming garden for wildlife.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

Every gardener has encountered advice that promises amazing results, from family traditions passed down through generations to the latest trend making the rounds on social media. How do you know what to trust?

In this episode, Erin talks with Bryce Battisti about what "research-based" really means and why it is a core part of the WSU Extension Master Gardener Program. Bryce shares his own journey from embracing popular gardening ideas to appreciating the value of research in helping gardeners make informed decisions.

Together, they explore how gardening recommendations are developed, why scientific understanding changes as new discoveries are made, and why local research is especially valuable for Washington gardeners. They also discuss practical ways to evaluate gardening advice, identify reliable sources, and avoid wasting time and money on untested practices.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

In this episode of The Evergreen Thumb, Erin Hoover chats with Julie Banken, a Master Gardener with a background in entomology, about creating pollinator-friendly gardens by rethinking traditional fall cleanup practices. Julie shares her passion for gardening with insects in mind, explaining how leaving leaves, stems, and other natural debris provides essential winter habitat for a wide variety of pollinators and beneficial insects. She encourages gardeners to view their yards as crucial parts of the ecosystem, highlights the importance of native plants, and offers practical advice for supporting insect life cycles—like leaving leaf mulch and standing stems through winter and only tidying up the next year. By making simple intentional changes, gardeners can help sustain the pollinators and insects that depend on them, making a positive impact right in their home gardens.

Every gardener has decisions they would make again…and a few they probably wouldn't.

In this episode, Erin Hoover reflects on the gardening choices that paid off, the ones that created more work than expected, and the unexpected surprises that have shaped her garden over the years. From self-seeding herbs that got out of control to volunteer flowers worth keeping, she shares practical lessons learned through trial, error, and observation.

Along the way, Erin discusses why investing in quality seed potatoes and garlic has been worthwhile, how redesigning her vegetable garden improved watering efficiency, and why a simple moisture meter completely changed the way she waters her garden.

If you're just starting out or even if you are a seasoned gardener, this is a reminder that every season teaches us something new.

Gardening changes as we do. Tasks that once felt easy may take more planning, different tools, or a new approach. In this episode of The Evergreen Thumb, we talk about practical ways gardeners can adapt their spaces and routines to keep gardening comfortably and confidently over time.

King County Extension Master Gardener Sally Bagshaw shares ideas for reducing physical strain, improving accessibility, and rethinking garden design to better fit changing needs. We discuss raised beds, pathways, ergonomic tools, lower-maintenance planting choices, and strategies that help gardeners stay connected to the activities we enjoy most.

In this episode, Lisa Taylor returns to share tips on saving water while gardening. Lisa focuses on how being intentional with water use improves soil health, efficient watering techniques, and drought-tolerant practices for thriving plants. She shares some of her favorite high-quality tools to make saving water easier. Listen to learn how to build resilient gardens that thrive with less water, perfect for hot summers and adapting to climate change.

In this episode of The Evergreen Thumb, we talk with Master Gardener Ed Adams about growing dahlias in Western Washington, including what it takes to manage a large collection of over 600 plants.

Ed shares why dahlias thrive in Sequim's unique climate and walks through practical, research-based approaches to growing them successfully. The conversation covers getting started with tubers, seasonal care, supporting healthy growth, and managing common garden challenges using an integrated pest management approach.

We also explore what changes when dahlias are grown at scale, along with tips for digging, dividing, and storing tubers for the next season.

Whether you're growing a few plants or planning something larger, this episode offers grounded, field-tested insight into making dahlias work in a Pacific Northwest garden.

There are a lot of resources mentioned in this episode. Find them on our website.

In this episode of The Evergreen Thumb, we talk with Dr. Joel Gardner from the WSU M.T. James Entomological Collection about native bees, including Dialictus sweat bees, and how new species are discovered. Joel explains how insect collections support research on pollinators and biodiversity in Washington, and why preserved specimens remain important for understanding ecological change over time.

Resources mentioned in this episode, along with a full transcript, can be found on our website. (link opens in new window)

Explore the development of a sensory garden designed to be accessible and therapeutic for neurodivergent individuals, veterans with PTSD, and others with sensory sensitivities. Learn about the design, purpose, and community impact of this innovative project.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

Slugs and snails are a constant frustration for gardeners in Western Washington, but trying to eliminate them completely isn't the goal, and it's not realistic.

In this episode, we're joined by Skagit County Master Gardener Diana Wisen to talk about why these pests thrive in our region, what role they play in the ecosystem, and how to manage them effectively in a home garden. We dig into slug behavior, life cycles, and the key moments when they're most vulnerable.

You'll come away with practical, research-based strategies that focus on control rather than eradication, helping you reduce damage while working with the natural systems in your garden.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

In this episode, Patrick Schults, WSU Extension forester, discusses the threat of emerald ash borer, an invasive insect that poses a significant risk to Washington's forests and urban trees. Learn about how it spreads, signs of infestation, and what communities can do to prepare and respond.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

In this solo episode, Erin shares her top 10 gardening tips for 2026. These are practical shifts that can make your garden easier to manage while helping plants handle stress such as inconsistent water, pests, and changing weather patterns.

You'll hear a mix of mindset shifts, common habits to stop, and a few practices worth adding to your routine. Topics include soil health, watering strategies, biodiversity in the garden, integrated pest management, and making site-driven plant choices.

Rather than overhauling everything, the goal is simple: choose one meaningful change this season and observe the results.

Referenced episodes and additional resources are available in the show notes on our website.

In this conversation, Colleen Adams-Schuppe, the executive director of the Yakima Area Arboretum, shares her journey and the history of the arboretum, highlighting its unique origin story as a community-driven initiative. She discusses the challenges and successes of curating a living landscape in a desert climate, the significance of various garden spaces, and the role of educational programs in fostering community engagement. Colleen emphasizes the importance of volunteers and community partners in maintaining the arboretum and outlines future aspirations for its growth and development.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

Most gardeners recognize honey bees, but in Washington, there are over 600 species of native bees doing much of the pollination work in our landscapes.

In this conversation, Anne Bulger, a WSU Master Gardener, discusses the significance of native bees in gardening and pollination. She shares her journey into the world of native bees, emphasizing their efficiency as pollinators compared to honey bees. The discussion covers common misconceptions about native bees, the importance of supporting them in gardens, and the diversity of bee species, particularly mining bees. Anne also highlights the role of native bees in maintaining healthy ecosystems and offers practical advice for gardeners to create bee-friendly habitats.

Resources mentioned in this episode, along with a full transcript, can be found on our website.

Good vegetable gardens aren't built by following rules; they're built by paying attention. In this episode, we step back from prescriptive advice and focus on how experienced gardeners actually make decisions.

Instead of chasing planting dates or perfect systems, we talk through how to read your landscape, choose crops that make sense for your goals and conditions, and time planting based on what plants respond to, not what the calendar says. You'll learn how to think about frost dates, growing degree days, and USDA zones without confusion, and why observation is one of the most valuable tools a gardener can develop.

This episode is about building judgment and confidence over time. If you're planning a new garden or maybe you're trying to understand why past advice hasn't quite worked, this episode will help you approach vegetable gardening with clearer expectations, better questions, and a stronger connection to your specific place.

Resources mentioned in this episode, along with a full transcript, can be found on our website.