Prosser, Washington, sits in USDA hardiness zone 7b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Expect cabbage, prickly pear, california poppy, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Prosser, 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 Prosser 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 Prosser — soil, climate, flood, and parcel records. How we handle your address.
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Prosser — the short answer
Prosser, Washington: USDA zone 7b, about 227 days between hard freezes, across 3K acres of city.
- USDA zone
- 7b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 21
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 3
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~227
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 3K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 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 7b is Prosser's average, not your lot's — a low corner or a tree line moves it. Against Prosser's 227-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Prosser
Each reading below is measured for Prosser itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredProsser runs about 227 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
MeasuredProsser sits in USDA hardiness zone 7b.
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 Prosser is in
Prosser sits in the Columbia Plateau — EPA Level III, inside the wider North American Deserts. That is read at Prosser's own centroid rather than borrowed from Benton County.
What Grows in Prosser
Every plant below cleared Prosser's own zone 7b and its 227-day season. Each card opens that plant's Washington profile. How we score.
Is it too late to plant in Prosser?
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 21; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 21 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 3 — 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 Prosser
Closest first, within ~10 miles of Prosser. Listing isn't leaking, and distance isn't exposure.
- BENTON COUNTY ROAD DEPT AREA 1 YARDUnderground Storage Tanks · 350 ft
- CROSBYUnderground Storage Tanks · 700 ft
- DUFAULTUnderground Storage Tanks · 700 ft
- PENDLETON GRAIN GROWERS INCUnderground Storage Tanks · 700 ft
- CARL C MOOREUnderground Storage Tanks · 850 ft
- PROSSER CITY OF MAINTENANCE YARDUnderground Storage Tanks · 1000 ft
- L & D MUNN FARMSUnderground Storage Tanks · 1000 ft
- BENTON RURAL ELECTRIC ASSOCIATIONUnderground Storage Tanks · 1100 ft
- GME WINE COUNTRYUnderground Storage Tanks · 1100 ft
- PROSSER MEMORIAL HOSPITALBrownfields · 1100 ft
- VALLEY VISTA MEDICAL GROUPBrownfields · 1200 ft
- MEDICAL COMPLEXUnderground Storage Tanks · 1300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Prosser'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 Prosser.
Total Sites
222
within ~10 miles of Prosser
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Prosser
Severity Distribution
within ~10 miles of Prosser
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Prosser, two things run higher than the national average within ~10 miles of Prosser — CAFO (3 sites) and Nitrate (80 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Prosser
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 Prosser average
Your land is one point inside Prosser
Everything above resolves to Prosser as a whole — one PHZM band and one 28°F frost record, read across 3K 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 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 Prosser Average
Prosser Average
- ●USDA Zones 7b, averaged across Prosser
- ●One soil character for all of Prosser
- ●Frost dates read at Prosser's scale: Mar 21 to Nov 3
YOUR Parcel
- ✓Your exact zone, not Prosser's 7b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Prosser
Pull a site-specific report for your exact address in Prosser, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Prosser averages can't show:
We read public map data around Prosser — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Prosser average
How we know this about Prosser
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 Prosser’s own record; 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 Prosser
When does frost risk typically end in Prosser?
The last hard freeze (28°F) in Prosser typically lands around Mar 21, 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 11.
When is the first frost in Prosser?
The first hard freeze (28°F) in Prosser typically arrives around Nov 3, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 20, so the watching starts about Oct 4 — about 227 days after the spring freeze cleared.
How long is the growing season in Prosser?
Measured between 28°F hard freezes, Prosser sees about 227 frost-free days — roughly Mar 21 through Nov 3, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 11 to Oct 20, about 192 days.
Is the soil safe to grow vegetables in Prosser?
The federal record around Prosser is a meaningful one — 222 documented sites, mostly Underground Storage Tanks entries (106), 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 Prosser?
From about Oct 4 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 3 (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 3. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Prosser's scale — its 7b band and its 227-day season. Your yard writes its own version of Prosser'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 Prosser’s own scale
6 of the readings below were taken at Prosser's own scale — its own ~227-day season between 28°F freezes, the 3,308 acres it covers and 222 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Prosser's own USDA hardiness band, zones 7bUSDA PHZM 2023
- Prosser's own 28°F hard-freeze dates, about Mar 21 and Nov 3 and the ~227-day span between themNOAA 1991–2020 Climate Normals
- 222 documented contamination sites on the federal record near Prosser, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Prosser's boundary and the 3,308 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7b and a ~227-day seasonGrowable Ground crop-matching engine
- The ecoregion at Prosser's own centroid, the Columbia PlateauUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Prosser's 3,308 acres read through its county's SSURGO summaryfrom Benton County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Benton 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 Benton County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Prosser's 3,308 acreswhy one lot differs from the next →
- Which side of Prosser you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,308 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 Prosser-wide figureread your own land →