Cowlitz County, in Washington, sits in USDA hardiness zone 8b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Reliable performers under these conditions include apple, cherry, hop, and grape; what your own ground favors still comes down to its soil, sun, and drainage.
Cowlitz County lies within the Pacific Northwest — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring
Cowlitz County holds more than one microclimate.
Soils and elevations shift across Cowlitz County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
8b
Last Frost (state avg.)
Mar 1 - Jun 1
First Frost (state avg.)
Sep 15 - Nov 15
County Area
730K acres
Hardiness Zone Range
Growing Season
Zone maps are averages across Cowlitz County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Cowlitz County
Across Cowlitz County, the ground is predominantly Ultisols, where Hazeldell, Olympic, and Vanson are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 5.6–6.1, moderately acidic. Rainfall drains through hydrologic group B soils.
Soil order
Ultisols
Drainage
Well drained
Prime farmland
6%
Hydric soils
4%
Soil still varies lot by lot — soil types explained.
What Grows in Cowlitz County
Plants matched to Cowlitz County's USDA zones 8b — each links to its full growing profile.
Growing Challenges in Washington
What an experienced grower plans around here — each one has a move.
Extreme rain divide: 90+ inches west, 6 inches east of Cascades
Plant to your side of the Cascades, not to the state — your exact spot's rainfall decides the whole plan.
East side requires irrigation — no rain from June through September
With no summer rain, drip lines and deep mulch are the growing season — set them up before June.
Slug and root rot pressure on the wet west side
Raise the beds, bait the slugs, and water mornings only — the wet-side trio that keeps roots and leaves healthy; extension has the details.
Short seasons at elevation in the Cascades and northeast corners
In the short-season corners, fast varieties plus a cold frame or tunnel reliably close the gap.
For cultivar selection, pest pressure, and planting-time guidance specific to Washington, the WSU Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Cowlitz County — and how to grow with it.
We checked the federal record across Cowlitz County — 517 documented sites across 7 of the 9 source types we track.
The most significant on record: 4 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Cowlitz County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
across Cowlitz County
Severity Distribution
across Cowlitz County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Cowlitz County, two things run higher than the national average — PFAS (6 sites) and Underground Storage Tanks (356 sites). That's not a problem with your land — it's information about it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Cowlitz County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Cowlitz County Average
- ●USDA Zones 8b
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Cowlitz County
Pull a site-specific report for your exact address in Cowlitz County, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Cowlitz County, Washington
- USDA Hardiness Zones: 8b (USDA PHZM 2023)
- Last Spring Frost (state avg.): Mar 1 - Jun 1 (NOAA 30-Year Climate Normals)
- First Fall Frost (state avg.): Sep 15 - Nov 15 (NOAA 30-Year Climate Normals)
- County Land Area: 730K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Cowlitz County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Cowlitz County, Washington?
Cowlitz County sits in USDA hardiness zone 8b, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
When does frost risk typically end in Cowlitz County?
Cowlitz County follows Washington's statewide frost window: last spring frost around Mar 1 - Jun 1 and first fall frost around Sep 15 - Nov 15, per NOAA 30-year climate normals (1991–2020). Frost dates shift with elevation and local microclimate, so watch your own site's cold pockets.
What vegetables grow in Cowlitz County?
Cowlitz County's zone 8b supports a wide range — strong performers include Apple, Cherry, Hop, Grape, and Blueberry. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Cowlitz County, really?
Officially, Cowlitz County sits in USDA zone 8b (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Cowlitz County?
The federal record around Cowlitz County runs heavier than most — 517 documented sites — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Just moved to Cowlitz County — what should I know before planting?
Start with three facts. Cowlitz County sits in USDA zone 8b, which sets what survives winter; the statewide frost window runs about Mar 1 - Jun 1 to Sep 15 - Nov 15 (NOAA 30-year climate normals); and 517 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Cowlitz County average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Washington's frost window, season length, and soil profile against the plant's real requirements.