Kelso, 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.
A short list that earns its place here — cabbage, fig, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Kelso, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Kelso lot. 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 Kelso — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Kelso — the short answer
Kelso, Washington: USDA zone 8b, about 251 days between hard freezes, across 5K acres of city.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 13
- Cowlitz County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Nov 19
- Cowlitz County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~251
- Cowlitz County normal — NOAA 1991–2020, nearest to this town
- City area
- 5K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Cowlitz County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 8b is Kelso's average, not your lot's — a low corner or a tree line moves it. Against Kelso's 251-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Kelso
Each reading below is measured for Kelso itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsKelso runs about 251 days between hard freezes (read from Cowlitz County, the closest normal to Kelso) — 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
MeasuredKelso 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 Kelso is in
Kelso sits in the Puget Lowland — EPA Level III, inside the wider Marine West Coast Forest. That is read at Kelso's own centroid, and it is not what its county reads: Cowlitz County is mostly Cascades. The wider page above you is answering a different question about different ground.
What Grows in Kelso
Every plant below cleared Kelso's own zone 8b and its 251-day season. Each card opens that plant's Washington profile. How we score.
Is it too late to plant in Kelso?
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. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
What's on the federal record near Kelso
Closest first, within ~10 miles of Kelso. Listing isn't leaking, and distance isn't exposure.
- KELSO MAINTENANCE SITEUnderground Storage Tanks · 1000 ft
- INTERSTATE WOOD PRODUCTSUnderground Storage Tanks · 1100 ft
- PLAS2FUEL CORPUnderground Storage Tanks · 1400 ft
- SILVER EAGLE COMPANYUnderground Storage Tanks · 1400 ft
- INTERSTATE WOOD PRODUCTS INCBrownfields · 1500 ft
- HEAVY HAULING COMPANY INCUnderground Storage Tanks · 1600 ft
- STORDAHL AND SONSUnderground Storage Tanks · 1700 ft
- NOR-TECH FABRICATION PAINTINGBrownfields · 1900 ft
- KELSO RMToxics Release Inventory · 2000 ft
- STEEL PAINTERS INCBrownfields · 2100 ft
- WA DOT KELSOUnderground Storage Tanks · 2300 ft
- JOHN WESTERVELTUnderground Storage Tanks · 2300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Kelso'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 Kelso.
Total Sites
418
within ~10 miles of Kelso
Risk Level
Elevated
Highest-severity
6 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Kelso
Severity Distribution
within ~10 miles of Kelso
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Kelso, two things run higher than the national average within ~10 miles of Kelso — Toxics Release Inventory (31 sites) and Superfund (6 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 Kelso
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 Kelso average
Your land is one point inside Kelso
Everything above resolves to Kelso as a whole — one PHZM band, read across 5K acres, with hard-freeze dates borrowed from Cowlitz County’s record because no 30-year normal resolves at this city’s own centroid. 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 city 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 local average.
Your Lot vs the Kelso Average
Kelso Average
- ●USDA Zones 8b, averaged across Kelso
- ●One soil character for all of Kelso
- ●Frost dates read at Kelso's scale: Mar 13 to Nov 19
YOUR Parcel
- ✓Your exact zone, not Kelso's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Kelso
Pull a site-specific report for your exact address in Kelso, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Kelso averages can't show:
We read public map data around Kelso — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kelso average
How we know this about Kelso
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Cowlitz County’s record, because none resolves here; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at city grain anywhere on this page — there is no city-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Kelso
When does frost risk typically end in Kelso?
The last hard freeze (28°F) in Kelso 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.
When is the first frost in Kelso?
The first hard freeze (28°F) in Kelso typically arrives around Nov 19, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 5, so the watching starts about Oct 20 — about 251 days after the spring freeze cleared.
How long is the growing season in Kelso?
Measured between 28°F hard freezes, Kelso 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 Kelso?
The federal record around Kelso is a meaningful one — 418 documented sites, mostly Underground Storage Tanks entries (294), the nearest Underground Storage Tanks record about 0.2 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.
How do I protect my plants from frost in Kelso?
From about Oct 20 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Nov 19 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Nov 19. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Kelso's scale — its 8b band and its 251-day season. Your yard writes its own version of Kelso's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Kelso’s own scale
5 of the readings below were taken at Kelso's own scale — the 5,206 acres it covers and 418 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Kelso's own USDA hardiness band, zones 8bUSDA PHZM 2023
- 418 documented contamination sites on the federal record near Kelso, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Kelso's boundary and the 5,206 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~251-day seasonGrowable Ground crop-matching engine
- Kelso sits in the Puget Lowland — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Kelso has no normal of its own, so its county's is the closest measured readfrom Cowlitz County
- Soil character — no town-scale survey exists, so Kelso's 5,206 acres read through its county's SSURGO summaryfrom Cowlitz County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Cowlitz County
- The growing challenges every Washington grower plans around — written at state scale, so they stay on the state guidefrom Washington
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Cowlitz County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Kelso's 5,206 acreswhy one lot differs from the next →
- Which side of Kelso you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 5,206 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Kelso-wide figureread your own land →