Grant County, in Washington, sits in USDA hardiness zone 7a — a zone band wide enough that plant choice, not possibility, is the interesting question.
A short list that earns its place here — cabbage, pawpaw, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Grant County lies within the Columbia Basin — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Grant County holds more than one microclimate.
Soils and elevations shift across Grant 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 Grant County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Grant County — the short answer
Grant County, Washington: USDA zone 7a, about 208 days between hard freezes, across 1.7M acres.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 3
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 28
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~208
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.7M 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 7a is Grant County's average, not your lot's — a low corner or a tree line moves it. Against Grant County's 208-day season, see what your own ground reads.
Heat in Grant County
Across a year, Grant County accumulates about 2,566 growing degree days above 50°F, about 853 more than the middle Washington county — ahead of every other Washington county. 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 Grant County
Across Grant County, the ground is predominantly Aridisols, where Quincy, Malaga, and Renslow are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 7.2–7.6, slightly alkaline. Rainfall drains through hydrologic group B soils.
Soil order
Aridisols
Drainage
Well drained
Hydric soils
2%
Soil still varies lot by lot — soil types explained.
How the ground varies across Grant County
The USDA soil survey maps 62% of Grant County as well drained — but another 34% drains differently: 28% somewhat excessively drained, 4% excessively drained.
Quincy is the most extensive named soil at 14% of mapped acres, then Malaga (10%) and Renslow (7%).
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 Grant County
Each reading below is measured for Grant 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 Grant 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 Grant County runs about pH 7.2–7.6, on the alkaline side.
Many vegetables cope, but acid-lovers like blueberries struggle, and iron and manganese lock up above about pH 7.5 — leaves yellow between the veins even in rich soil.
Elemental sulfur and generous organic matter lower pH slowly for the beds that need it; test first so you add only what the soil actually calls for.
USDA NRCS SSURGO
Season length
MeasuredGrant County runs about 208 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
MeasuredGrant County sits in USDA hardiness zone 7a.
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 Grant County is in
Grant County sits in the Columbia Plateau — EPA Level III, inside the wider North American Deserts. One consistent ecological setting across the whole county.
What Grows in Grant County
We scored all 1,086 plants against Grant County's own USDA zone 7a and its own 208-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 Grant County?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 6; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 3 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 28 — 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.
Documented around Grant County
- monarch butterfly6 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Grant County
USGS estimates 263,441 lb of Glyphosate on Grant County farmland in 2019, its largest by weight, ahead of Chlorpyrifos (103,394 lb) and 2,4-d (68,011 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 Grant County — and how to grow with it.
We checked the federal record across Grant County — 963 documented sites across 8 of the 9 source types we track.
The most significant on record: 8 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Grant County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Grant County
Closest first, across Grant County. Listing isn't leaking, and distance isn't exposure.
- 20N/26E-23N01 PE16BNitrate · 3.1 mi
- CALLOWAY FARMSUnderground Storage Tanks · 3.1 mi
- BILL TURNBULLUnderground Storage Tanks · 3.3 mi
- FARM PROPERTYUnderground Storage Tanks · 3.3 mi
- EPHRATA SCHOOL DISTRICT BUS MAINT YARDUnderground Storage Tanks · 3.3 mi
- GRANT PUD EPHRATA YARD ANNEXUnderground Storage Tanks · 3.3 mi
- CENTRAL WASHINGTON CONCRETEUnderground Storage Tanks · 3.3 mi
- UNOCAL 0191Underground Storage Tanks · 3.3 mi
- CLARENCE COXUnderground Storage Tanks · 3.3 mi
- 19N/26E-01R01Nitrate · 3.7 mi
- STETNER BROTHERS SITE 1Underground Storage Tanks · 3.9 mi
- 20N/26E-21A01Nitrate · 4.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Grant 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 Grant County.
Severity Distribution
across Grant County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Grant County, Nitrate runs higher than the national average — 352 sites across Grant County. That's not a problem with your land — it's information about it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Grant 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 Grant County average
Your land is one point inside Grant County
Everything above resolves to Grant County as a whole — one PHZM band and one county frost record, read across 1.7M 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 Grant County Average
Grant County Average
- ●USDA Zones 7a, averaged across Grant County
- ●One soil character for all of Grant County
- ●Frost dates read at Grant County's scale: Apr 3 to Oct 28
YOUR Parcel
- ✓Your exact zone, not Grant County's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Grant County
Pull a site-specific report for your exact address in Grant County, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Grant County averages can't show:
We read public map data around Grant County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Grant County average
How we know this about Grant 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 Grant County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Grant County
When does frost risk typically end in Grant County?
The last hard freeze (28°F) in Grant County typically lands around Apr 3, 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 24.
How long is the growing season in Grant County?
Measured between 28°F hard freezes, Grant County sees about 208 frost-free days — roughly Apr 3 through Oct 28, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 24 to Oct 14, about 173 days.
Is the soil safe to grow vegetables in Grant County?
The federal record around Grant County is a meaningful one — 963 documented sites, mostly Underground Storage Tanks entries (471), the nearest Nitrate record about 3.1 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.
Everything above is measured at Grant County's scale — its 7a band and its 208-day season. Your yard writes its own version of Grant 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 Grant County’s own scale
9 of the readings below were taken at Grant County's own scale — its own ~208-day span between 28°F freezes, the 3 most extensive soil series mapped here and 963 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Grant County's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Grant County's own 28°F hard-freeze dates and its ~208-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Grant CountyUSDA NRCS SSURGO
- 963 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 3.1 miles outFederal environmental registers
- Grant County's boundary and the 1,714,913 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~208-day seasonGrowable Ground crop-matching engine
- Grant County sitting wholly inside the Columbia PlateauUS EPA Level III Ecoregions
- Open occurrence records documented in Grant County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Grant 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 Grant County — the ~208 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 Grant County's 1,714,913 acreswhy one lot differs from the next →
- Which of those 963 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 Grant Countyread your own land →