Clark County, in Washington, sits in USDA hardiness zone 8b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
The conditions favor cabbage, fig, california poppy, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Clark 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
Clark County holds more than one microclimate.
Soils and elevations shift across Clark 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 Clark County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Clark County — the short answer
Clark County, Washington: USDA zone 8b, about 217 days between hard freezes, across 402K acres.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 28
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 31
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~217
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 402K 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 Clark County's average, not your lot's — a low corner or a tree line moves it. Against Clark County's 217-day season, see what your own ground reads.
Heat in Clark County
Across a year, Clark County accumulates about 1,865 growing degree days above 50°F, about 152 more than the middle Washington county — ahead of 25 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 Clark County
Across Clark County, the ground is predominantly Andisols, where Cinebar, Olympic, and Hesson are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 5.5–5.8, moderately acidic. Rainfall drains through hydrologic group B soils.
Soil order
Andisols
Drainage
Well drained
Prime farmland
23%
Hydric soils
9%
Soil still varies lot by lot — soil types explained.
How the ground varies across Clark County
The USDA soil survey maps 73% of Clark County as well drained — but another 25% drains differently: 12% moderately well drained, 8% poorly drained.
Cinebar is the most extensive named soil at 22% of mapped acres, then Olympic (15%) and Hesson (12%).
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 Clark County
Each reading below is measured for Clark 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 Clark 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 Clark County runs about pH 5.5–5.8, 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
MeasuredClark County runs about 217 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
MeasuredClark 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 Clark County is in
Clark County spans 2 EPA Level III ecoregions — Willamette Valley (57%) and Cascades (43%). 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 Clark County
We scored all 1,086 plants against Clark County's own USDA zone 8b and its own 217-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 Clark 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 28; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 28 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 31 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
Documented around Clark County
Survey cells within 31 miles of Clark County checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 555 miles off. What to watch for.
What gets applied to farmland in Clark County
USGS estimates 2,340 lb of 2,4-d on Clark County farmland in 2019, its largest by weight, ahead of Triclopyr (1,702 lb) and Glyphosate (1,685 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 Clark County — and how to grow with it.
We checked the federal record across Clark County — 1,068 documented sites across 7 of the 9 source types we track.
The most significant on record: 14 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Clark 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.
What's on the federal record near Clark County
Closest first, across Clark County. Listing isn't leaking, and distance isn't exposure.
- CLARK COUNTY PUBLIC WORKS TUKES MTNUnderground Storage Tanks · 1.2 mi
- MADDOX INDUSTRIAL TRANSFORMERBrownfields · 1.2 mi
- FIRST CHOICE MKT HOCKINSON CHEVRONUnderground Storage Tanks · 1.5 mi
- HOCKINSON SCHOOL DISTRICT 98Underground Storage Tanks · 1.6 mi
- OLDCASTLE BUILDINGENVELOPE VANCOUVERBrownfields · 1.7 mi
- CEDARS GOLF CLUBUnderground Storage Tanks · 2.1 mi
- DORSEY BUS SERVICE INCUnderground Storage Tanks · 2.2 mi
- BATTLEGROUND STATE PARKUnderground Storage Tanks · 2.2 mi
- BATTLE GROUND INNUnderground Storage Tanks · 2.2 mi
- LEWIS ROCK & REDI MIX INCUnderground Storage Tanks · 2.2 mi
- TOFTDAHL DRUM SITESuperfund · 2.2 mi
- 03N/02E-02D01Nitrate · 2.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Clark 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 Clark County.
Sources Checked
across Clark County
Severity Distribution
across Clark County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Clark County, two things run higher than the national average across Clark County — Toxics Release Inventory (78 sites) and Superfund (14 sites). That's not a problem with your land — it's information about it.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Clark 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 Clark County average
Your land is one point inside Clark County
Everything above resolves to Clark County as a whole — one PHZM band and one county frost record, read across 402K 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 Clark County Average
Clark County Average
- ●USDA Zones 8b, averaged across Clark County
- ●One soil character for all of Clark County
- ●Frost dates read at Clark County's scale: Mar 28 to Oct 31
YOUR Parcel
- ✓Your exact zone, not Clark County's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Clark County
Pull a site-specific report for your exact address in Clark County, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Clark County averages can't show:
We read public map data around Clark County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Clark County average
How we know this about Clark 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 Clark County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Clark County
When does frost risk typically end in Clark County?
The last hard freeze (28°F) in Clark County typically lands around Mar 28, 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 18.
How long is the growing season in Clark County?
Measured between 28°F hard freezes, Clark County sees about 217 frost-free days — roughly Mar 28 through Oct 31, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 18 to Oct 17, about 182 days.
Is the soil safe to grow vegetables in Clark County?
The federal record around Clark County runs heavier than most — 1,068 documented sites, mostly Underground Storage Tanks entries (640), the nearest Underground Storage Tanks record about 1.2 miles out — 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.
Everything above is measured at Clark County's scale — its 8b band and its 217-day season. Your yard writes its own version of Clark 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 Clark County’s own scale
8 of the readings below were taken at Clark County's own scale — its own ~217-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,068 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Clark County's own USDA hardiness band, zones 8bUSDA PHZM 2023
- Clark County's own 28°F hard-freeze dates and its ~217-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Clark CountyUSDA NRCS SSURGO
- 1,068 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 1.2 miles outFederal environmental registers
- Clark County's boundary and the 402,245 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~217-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Clark County spans, Willamette Valley the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Clark 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 Clark County — the ~217 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 Clark County's 402,245 acreswhy one lot differs from the next →
- Which of those 1,068 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 Clark Countyread your own land →