Seattle, Washington, sits in USDA hardiness zone 9a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Well-matched crops include kale, potato, garlic, and western red cedar, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Seattle, 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 Seattle 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 Seattle — soil, climate, flood, and parcel records. How we handle your address.
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Seattle — the short answer
Seattle, Washington: USDA zone 9a, about 252 days between hard freezes, across 54K acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 14
- King County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Nov 21
- King County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~252
- King County normal — NOAA 1991–2020, nearest to this town
- City area
- 54K 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 King County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Seattle's average, not your lot's — a low corner or a tree line moves it. Against Seattle's 252-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Seattle
Each reading below is measured for Seattle itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsSeattle runs about 252 days between hard freezes (read from King County, the closest normal to Seattle) — 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
MeasuredSeattle sits in USDA hardiness zone 9a.
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 Seattle is in
Seattle sits in the Puget Lowland — EPA Level III, inside the wider Marine West Coast Forest. That is read at Seattle's own centroid rather than borrowed from King County.
What Grows in Seattle
Plants matched to Seattle's USDA zones 9a, ordered by how much hardiness margin each has here — the ones with room to spare at both ends of this town's band lead. Each links to its full growing profile.
Is it too late to plant in Seattle?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 14; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 14 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 21 — 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's on the federal record near Seattle
Closest first, within ~10 miles of Seattle. Listing isn't leaking, and distance isn't exposure.
- Pacific Science CenterUnderground Storage Tanks · 100 ft
- BEN BRIDGE JEWELERBrownfields · 300 ft
- DEAN STRALEY'S BPUnderground Storage Tanks · 450 ft
- UNION OIL 0355Underground Storage Tanks · 650 ft
- THE FAMOUS PACIFIC DESSERT COMPANYUnderground Storage Tanks · 700 ft
- KOMO RADIO & TVUnderground Storage Tanks · 700 ft
- THIRD AVENUE PRODUCTIONSUnderground Storage Tanks · 800 ft
- UNIGEN INC SEATTLEBrownfields · 850 ft
- CYRUS BIOTECHNOLOGY INC SEATTLEBrownfields · 850 ft
- ADVANCED CELLULAR DYNAMICS INC THROUGH SALISH BIOSCIENCEBrownfields · 850 ft
- COX MEDIA GROUP SEATTLEUnderground Storage Tanks · 850 ft
- Fifth and Broad PropertyUnderground Storage Tanks · 900 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Seattle'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 Seattle.
Sources Checked
within ~10 miles of Seattle
Severity Distribution
within ~10 miles of Seattle
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Seattle, Underground Storage Tanks runs higher than the national average — 2,248 sites within ~10 miles of Seattle. That's not a problem with your land — it's information about it.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Seattle
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 Seattle average
Your land is one point inside Seattle
Everything above resolves to Seattle as a whole — one PHZM band, read across 54K acres, with hard-freeze dates borrowed from King 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 Seattle Average
Seattle Average
- ●USDA Zones 9a, averaged across Seattle
- ●One soil character for all of Seattle
- ●Frost dates read at Seattle's scale: Mar 14 to Nov 21
YOUR Parcel
- ✓Your exact zone, not Seattle's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Seattle
Pull a site-specific report for your exact address in Seattle, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Seattle averages can't show:
We read public map data around Seattle — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Seattle average
How we know this about Seattle
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 King 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 Seattle
When does frost risk typically end in Seattle?
The last hard freeze (28°F) in Seattle typically lands around Mar 14, 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 4.
When is the first frost in Seattle?
The first hard freeze (28°F) in Seattle typically arrives around Nov 21, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 7, so the watching starts about Oct 22 — about 252 days after the spring freeze cleared.
How long is the growing season in Seattle?
Measured between 28°F hard freezes, Seattle sees about 252 frost-free days — roughly Mar 14 through Nov 21, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 4 to Nov 7, about 217 days.
Is the soil safe to grow vegetables in Seattle?
The federal record around Seattle runs heavier than most — 3,375 documented sites, mostly Underground Storage Tanks entries (2,248), the nearest Underground Storage Tanks record under a tenth of a mile 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.
How do I protect my plants from frost in Seattle?
From about Oct 22 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 21 (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 21. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Seattle's scale — its 9a band and its 252-day season. Your yard writes its own version of Seattle'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 Seattle’s own scale
4 of the readings below were taken at Seattle's own scale — the 53,760 acres it covers and 3,375 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Seattle's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 3,375 documented contamination sites on the federal record near Seattle, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Seattle's boundary and the 53,760 acres inside itUS Census TIGER/Line 2025
- The ecoregion at Seattle's own centroid, the Puget LowlandUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Seattle has no normal of its own, so its county's is the closest measured readfrom King County
- Soil character — no town-scale survey exists, so Seattle's 53,760 acres read through its county's SSURGO summaryfrom King County
- The candidate plant list — Washington's curated set, filtered to this zone band and re-ordered by how much margin each has herefrom Washington
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom King 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 King County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Seattle's 53,760 acreswhy one lot differs from the next →
- Which side of Seattle you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 53,760 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Seattle-wide figureread your own land →
More in Washington
Growing region
Nearby growing guides