Cosmopolis, Washington, sits in USDA hardiness zone 9a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Reliable performers under these conditions include artichoke, fig, california poppy, and cabbage; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Cosmopolis, 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 Cosmopolis 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 Cosmopolis — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Cosmopolis — the short answer
Cosmopolis, Washington: USDA zone 9a, about 256 days between hard freezes, across 891 acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 9
- Grays Harbor County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Nov 20
- Grays Harbor County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~256
- Grays Harbor County normal — NOAA 1991–2020, nearest to this town
- City area
- 891 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 Grays Harbor County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Cosmopolis's average, not your lot's — a low corner or a tree line moves it. Against Cosmopolis's 256-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Cosmopolis
Each reading below is measured for Cosmopolis itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsCosmopolis runs about 256 days between hard freezes (read from Grays Harbor County, the closest normal to Cosmopolis) — 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
MeasuredCosmopolis 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 Cosmopolis is in
Cosmopolis sits in the Coast Range — EPA Level III, inside the wider Marine West Coast Forest. That is read at Cosmopolis's own centroid rather than borrowed from Grays Harbor County.
What Grows in Cosmopolis
Every plant below cleared Cosmopolis's own zone 9a and its 256-day season. Each card opens that plant's Washington profile. How we score.
Is it too late to plant in Cosmopolis?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Feb 9; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 9 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 20 — 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 Cosmopolis
Closest first, within ~10 miles of Cosmopolis. Listing isn't leaking, and distance isn't exposure.
- PRECISION MARINEUnderground Storage Tanks · 350 ft
- BRAMSTEDT SALES INCUnderground Storage Tanks · 550 ft
- COSMOPOLIS CITY OFUnderground Storage Tanks · 650 ft
- MAXI MINI MARTUnderground Storage Tanks · 950 ft
- UPRR COSMOPOLISUnderground Storage Tanks · 1000 ft
- HIGHLAND GOLF COURSEUnderground Storage Tanks · 1200 ft
- ARTIC TAVERN RV PARKUnderground Storage Tanks · 1300 ft
- COSMOPOLIS TRUCK SHOPUnderground Storage Tanks · 1700 ft
- COSMOPOLIS SCHOOL DISTRICT 99Underground Storage Tanks · 1900 ft
- COUNTY MAINTENANCE SHOPUnderground Storage Tanks · 1900 ft
- WA DOT COSMOPOLIS CITY OF PUBLIC UTILITIES SHOPUnderground Storage Tanks · 1900 ft
- INDUSTRIAL CUT STOCK INCUnderground Storage Tanks · 0.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Cosmopolis'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 Cosmopolis.
Total Sites
250
within ~10 miles of Cosmopolis
Risk Level
Elevated
Highest-severity
3 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Cosmopolis
Severity Distribution
within ~10 miles of Cosmopolis
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Cosmopolis, Underground Storage Tanks runs higher than the national average — 208 sites within ~10 miles of Cosmopolis. 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 Cosmopolis
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 Cosmopolis average
Your land is one point inside Cosmopolis
Everything above resolves to Cosmopolis as a whole — one PHZM band, read across 891 acres, with hard-freeze dates borrowed from Grays Harbor 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 Cosmopolis Average
Cosmopolis Average
- ●USDA Zones 9a, averaged across Cosmopolis
- ●One soil character for all of Cosmopolis
- ●Frost dates read at Cosmopolis's scale: Mar 9 to Nov 20
YOUR Parcel
- ✓Your exact zone, not Cosmopolis's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Cosmopolis
Pull a site-specific report for your exact address in Cosmopolis, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Cosmopolis averages can't show:
We read public map data around Cosmopolis — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Cosmopolis average
How we know this about Cosmopolis
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 Grays Harbor 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 Cosmopolis
When does frost risk typically end in Cosmopolis?
The last hard freeze (28°F) in Cosmopolis typically lands around Mar 9, 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 Mar 30.
When is the first frost in Cosmopolis?
The first hard freeze (28°F) in Cosmopolis typically arrives around Nov 20, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 6, so the watching starts about Oct 21 — about 256 days after the spring freeze cleared.
How long is the growing season in Cosmopolis?
Measured between 28°F hard freezes, Cosmopolis sees about 256 frost-free days — roughly Mar 9 through Nov 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 30 to Nov 6, about 221 days.
Is the soil safe to grow vegetables in Cosmopolis?
The federal record around Cosmopolis is a meaningful one — 250 documented sites, mostly Underground Storage Tanks entries (208), the nearest Underground Storage Tanks record under a tenth of a mile 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 Cosmopolis?
From about Oct 21 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 20 (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 20. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Cosmopolis's scale — its 9a band and its 256-day season. Your yard writes its own version of Cosmopolis'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 Cosmopolis’s own scale
5 of the readings below were taken at Cosmopolis's own scale — the 891 acres it covers and 250 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Cosmopolis's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 250 documented contamination sites on the federal record near Cosmopolis, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Cosmopolis's boundary and the 891 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~256-day seasonGrowable Ground crop-matching engine
- The ecoregion at Cosmopolis's own centroid, the Coast RangeUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Cosmopolis has no normal of its own, so its county's is the closest measured readfrom Grays Harbor County
- Soil character — no town-scale survey exists, so Cosmopolis's 891 acres read through its county's SSURGO summaryfrom Grays Harbor County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Grays Harbor 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 Grays Harbor County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Cosmopolis's 891 acreswhy one lot differs from the next →
- Which side of Cosmopolis you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 891 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 Cosmopolis-wide figureread your own land →