Ahtanum, Washington, sits in USDA hardiness zone 7a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Expect cabbage, pawpaw, 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 Ahtanum, 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 Ahtanum 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 Ahtanum — soil, climate, flood, and parcel records. How we handle your address.
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Ahtanum — the short answer
Ahtanum, Washington: USDA zone 7a, about 208 days between hard freezes, across 5K acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 31
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 25
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~208
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 5K 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 7a is Ahtanum's average, not your lot's — a low corner or a tree line moves it. Against Ahtanum's 208-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Ahtanum
Each reading below is measured for Ahtanum itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredAhtanum 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
MeasuredAhtanum 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 Ahtanum is in
Ahtanum sits in the Columbia Plateau — EPA Level III, inside the wider North American Deserts. That is read at Ahtanum's own centroid rather than borrowed from Yakima County.
What Grows in Ahtanum
Every plant below cleared Ahtanum's own zone 7a and its 208-day season. Each card opens that plant's Washington profile. How we score.
Is it too late to plant in Ahtanum?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 3; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 31 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 25 — 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 Ahtanum
Closest first, within ~10 miles of Ahtanum. Listing isn't leaking, and distance isn't exposure.
- WEST VALLEY BUS GARAGEUnderground Storage Tanks · 1100 ft
- AHTANUM GENERAL STOREUnderground Storage Tanks · 1400 ft
- AHTANUM TEXACO FOOD MARTUnderground Storage Tanks · 1800 ft
- CLASEN FRUIT AND COLD STORAGEUnderground Storage Tanks · 0.5 mi
- YAKIMA COUNTY FIRE DISTRICT NO 12 AHTANUMUnderground Storage Tanks · 0.8 mi
- 12N/18E-05G02Nitrate · 1.0 mi
- 12N/18E-05J01Nitrate · 1.1 mi
- WEST VALLEY SCHOOL DISTRICT 208Underground Storage Tanks · 1.3 mi
- WEST VALLEY SCHOOL DIST FORMER HIGH SCHOOL CAMPUS BOILER BLDUnderground Storage Tanks · 1.4 mi
- TOWN PUMP N PANTRYUnderground Storage Tanks · 1.8 mi
- A & G TRUCKINGUnderground Storage Tanks · 1.9 mi
- MEADOWBROOK CONVENIENCE CENTERUnderground Storage Tanks · 1.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Ahtanum'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 Ahtanum.
Sources Checked
within ~10 miles of Ahtanum
Severity Distribution
within ~10 miles of Ahtanum
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Ahtanum, Underground Storage Tanks runs higher than the national average — 433 sites within ~10 miles of Ahtanum. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Ahtanum
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 Ahtanum average
Your land is one point inside Ahtanum
Everything above resolves to Ahtanum as a whole — one PHZM band and one 28°F frost record, read across 5K 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 town 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 Ahtanum Average
Ahtanum Average
- ●USDA Zones 7a, averaged across Ahtanum
- ●One soil character for all of Ahtanum
- ●Frost dates read at Ahtanum's scale: Mar 31 to Oct 25
YOUR Parcel
- ✓Your exact zone, not Ahtanum's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Ahtanum
Pull a site-specific report for your exact address in Ahtanum, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Ahtanum averages can't show:
We read public map data around Ahtanum — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Ahtanum average
How we know this about Ahtanum
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Ahtanum’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 town grain anywhere on this page — there is no town-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 Ahtanum
When does frost risk typically end in Ahtanum?
The last hard freeze (28°F) in Ahtanum typically lands around Mar 31, 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 21.
When is the first frost in Ahtanum?
The first hard freeze (28°F) in Ahtanum typically arrives around Oct 25, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 11, so the watching starts about Sep 25 — about 208 days after the spring freeze cleared.
How long is the growing season in Ahtanum?
Measured between 28°F hard freezes, Ahtanum sees about 208 frost-free days — roughly Mar 31 through Oct 25, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 21 to Oct 11, about 173 days.
Is the soil safe to grow vegetables in Ahtanum?
The federal record around Ahtanum runs heavier than most — 619 documented sites, mostly Underground Storage Tanks entries (433), the nearest Underground Storage Tanks record about 0.2 miles 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 Ahtanum?
From about Sep 25 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 Oct 25 (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 Oct 25. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Ahtanum's scale — its 7a band and its 208-day season. Your yard writes its own version of Ahtanum'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 Ahtanum’s own scale
6 of the readings below were taken at Ahtanum's own scale — its own ~208-day season between 28°F freezes, the 4,942 acres it covers and 619 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Ahtanum's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Ahtanum's own 28°F hard-freeze dates, about Mar 31 and Oct 25 and the ~208-day span between themNOAA 1991–2020 Climate Normals
- 619 documented contamination sites on the federal record near Ahtanum, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Ahtanum's boundary and the 4,942 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~208-day seasonGrowable Ground crop-matching engine
- The ecoregion at Ahtanum's own centroid, the Columbia PlateauUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Ahtanum's 4,942 acres read through its county's SSURGO summaryfrom Yakima County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Yakima 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 Yakima County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Ahtanum's 4,942 acreswhy one lot differs from the next →
- Which side of Ahtanum you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,942 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 Ahtanum-wide figureread your own land →