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 cabbage, fig, california poppy, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Cowlitz County lies within the Lower Columbia / Southwest Washington (Vancouver-Longview) and the Pacific Northwest — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
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 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Cowlitz County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Cowlitz County — the short answer
Cowlitz County, Washington: USDA zone 8b, about 251 days between hard freezes, across 730K acres.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 13
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 19
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~251
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 730K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 8b is Cowlitz County's average, not your lot's — a low corner or a tree line moves it. Against Cowlitz County's 251-day season, see what your own ground reads.
Heat in Cowlitz County
Across a year, Cowlitz County accumulates about 1,547 growing degree days above 50°F, about 166 fewer than the middle Washington county — ahead of 16 of Washington’s 39 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
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.
How the ground varies across Cowlitz County
The USDA soil survey maps 84% of Cowlitz County as well drained — but another 14% drains differently: 5% moderately well drained, 4% somewhat poorly drained.
Hazeldell is the most extensive named soil at 13% of mapped acres, then Olympic (11%) and Vanson (5%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Cowlitz County
Each reading below is measured for Cowlitz County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Cowlitz County are well drained, in hydrologic group B — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Cowlitz County runs about pH 5.6–6.1, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Season length
MeasuredCowlitz County runs about 251 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredCowlitz County sits in USDA hardiness zone 8b.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Cowlitz County is in
Cowlitz County spans 3 EPA Level III ecoregions — Cascades (59%), Puget Lowland (21%) and Coast Range (18%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Cowlitz County
We scored all 1,086 plants against Cowlitz County's own USDA zone 8b and its own 251-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Washington profile.
Is it too late to plant in Cowlitz County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Feb 13; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 19 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
What gets applied to farmland in Cowlitz County
USGS estimates 12,003 lb of Glyphosate on Cowlitz County farmland in 2019, its largest by weight, ahead of Bromoxynil (859 lb) and Metolachlor-s (710 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
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 (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Cowlitz County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Cowlitz County
Closest first, across Cowlitz County. Listing isn't leaking, and distance isn't exposure.
- Red StarMining · 3.1 mi
- KELSO CITY OFPFAS · 4.9 mi
- KELSO SUB DIVISION3 LS52 MP97Underground Storage Tanks · 7.6 mi
- QZQ RMLUnderground Storage Tanks · 7.7 mi
- KALAMA CITY OFPFAS · 7.8 mi
- KID VALLEY SITE STORAGE MAINTENANCE SHEDUnderground Storage Tanks · 8.0 mi
- REESE BROTHERS INCUnderground Storage Tanks · 8.3 mi
- ROY FILLAUnderground Storage Tanks · 8.9 mi
- 10N/01W-25J01Nitrate · 9.1 mi
- DREW'S GROCERY & SERVICEUnderground Storage Tanks · 9.2 mi
- BAUER PROPERTYUnderground Storage Tanks · 9.2 mi
- TOUTLE LAKE SCHOOL DISTRICT 130Underground Storage Tanks · 9.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Cowlitz County's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Cowlitz County.
Total Sites
517
across Cowlitz County
Risk Level
Elevated
Highest-severity
4 Superfund sites (none NPL-listed)
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 across Cowlitz County — 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 1,086 plant recommendations.
25+ data sources read at your address, not the Cowlitz County average
Your land is one point inside Cowlitz County
Everything above resolves to Cowlitz County as a whole — one PHZM band and one county frost record, read across 730K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at county scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better county average.
Your Lot vs the Cowlitz County Average
Cowlitz County Average
- ●USDA Zones 8b, averaged across Cowlitz County
- ●One soil character for all of Cowlitz County
- ●Frost dates read at Cowlitz County's scale: Mar 13 to Nov 19
YOUR Parcel
- ✓Your exact zone, not Cowlitz County's 8b
- ✓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 lot that Cowlitz County averages can't show:
We read public map data around Cowlitz County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Cowlitz County average
How we know this about Cowlitz County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Cowlitz County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Cowlitz County
When does frost risk typically end in Cowlitz County?
The last hard freeze (28°F) in Cowlitz County typically lands around Mar 13, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Apr 3.
How long is the growing season in Cowlitz County?
Measured between 28°F hard freezes, Cowlitz County sees about 251 frost-free days — roughly Mar 13 through Nov 19, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 3 to Nov 5, about 216 days.
Is the soil safe to grow vegetables in Cowlitz County?
The federal record around Cowlitz County is a meaningful one — 517 documented sites, mostly Underground Storage Tanks entries (356), the nearest Mining record about 3.1 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
Everything above is measured at Cowlitz County's scale — its 8b band and its 251-day season. Your yard writes its own version of Cowlitz County's numbers: 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.
What this page reads at Cowlitz County’s own scale
8 of the readings below were taken at Cowlitz County's own scale — its own ~251-day span between 28°F freezes, the 3 most extensive soil series mapped here and 517 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Cowlitz County's own USDA hardiness band, zones 8bUSDA PHZM 2023
- Cowlitz County's own 28°F hard-freeze dates and its ~251-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Cowlitz CountyUSDA NRCS SSURGO
- 517 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Mining record about 3.1 miles outFederal environmental registers
- Cowlitz County's boundary and the 730,352 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~251-day seasonGrowable Ground crop-matching engine
- The 3 ecoregions Cowlitz County spans, Cascades the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Cowlitz County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Washington grower plans around — written at state scale, so they stay on the state guidefrom Washington
What this page can’t tell you
- How the season shifts across Cowlitz County — the ~251 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Cowlitz County's 730,352 acreswhy one lot differs from the next →
- Which of those 517 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Cowlitz Countyread your own land →