About HortGuide
Regional plant knowledge, built for the people who actually do the work.
HortGuide is a horticulture field guide for Western Washington. Every profile, every guide, every recommendation is written for this climate, this soil, and these conditions - not adapted from national data.
What this site does
Most plant care information online is written for a national audience and then loosely tagged with zone numbers. That approach breaks down when you need to know whether to spray copper on your cherry tree this week, or whether the leaf spots on your bigleaf maple are cosmetic or structural.
HortGuide exists to close that gap. The site covers three areas: arboriculture - caring for trees and shrubs in managed landscapes; nursery horticulture - how plants are grown, selected, and evaluated; and landscape horticulture - the design and maintenance of planted spaces. Everything is anchored to Western Washington's maritime climate.
The reference library is the backbone. It tracks host associations between plants and their diseases and pests, documents susceptibility ratings, and maps management timing to regional conditions. The guides translate that data into practical recommendations - what to watch for, when to act, and what to skip.
The Library in Numbers
Documented plant-disease and plant-pest relationships
Written By
Chris Welch
ISA Certified Arborist
I started in a greenhouse during high school, pivoted to landscape horticulture in college, and spent the years after graduation moving through the industry - climbing arborist, wholesale nursery operations, arboricultural consulting. Each role taught me something the others couldn't.
HortGuide is where I document what I learn. Every recommendation comes from someone who works with these plants in this climate. When I cite extension research, I've read the source material. When I say a treatment works here, I mean here - not "the Pacific Northwest" in the vague, Seattle-to-Medford sense.
If something on this site is wrong, I want to know about it. The goal is to be useful and accurate, not to publish volume.
Credentials
Experience
Location
How the data works
Plant, disease, and pest profiles contain verified facts - taxonomy, host ranges, lifecycle thresholds, susceptibility ratings. No opinions, no regional spin. The data stands on its own.
Guides take that data and apply regional judgment - what to do here, when to do it, and what to skip. Every recommendation is sourced, and every source is cited.
WSU Extension, Oregon State, PNW Handbooks, USDA, and peer-reviewed research. When sources conflict, the conflict is surfaced - not silently resolved.
Get in touch
Questions, corrections, or collaboration inquiries.
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