Sweetwater, Idaho, sits in USDA hardiness zone 7b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Among the crops suited to this profile: cabbage, prickly pear, california poppy, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in Sweetwater, 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 Sweetwater 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 Sweetwater — soil, climate, flood, and parcel records. How we handle your address.
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Sweetwater — the short answer
Sweetwater, Idaho: USDA zone 7b, about 241 days between hard freezes, across 763 acres of town.
- USDA zone
- 7b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~241
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 763 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 Sweetwater's average, not your lot's — a low corner or a tree line moves it. Against Sweetwater's 241-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Sweetwater
Each reading below is measured for Sweetwater itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSweetwater runs about 241 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
MeasuredSweetwater 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 Sweetwater is in
Sweetwater sits in the Columbia Plateau — EPA Level III, inside the wider North American Deserts. That is read at Sweetwater's own centroid rather than borrowed from Nez Perce County.
What Grows in Sweetwater
Every plant below cleared Sweetwater's own zone 7b and its 241-day season. Each card opens that plant's Idaho profile. How we score.
Is it too late to plant in Sweetwater?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Feb 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 12 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
What's on the federal record near Sweetwater
Closest first, within ~10 miles of Sweetwater. Listing isn't leaking, and distance isn't exposure.
- 35N 04W 14DDD1Nitrate · 1700 ft
- US DOI NPS NEZ PERCE NATIONAL HIST PARKBrownfields · 0.9 mi
- NIMIIPUU HEALTH SERVICE LAPWAIBrownfields · 2.1 mi
- 35N 04W 02ABD1Nitrate · 2.9 mi
- MCINTOSH & SONSUnderground Storage Tanks · 3.1 mi
- BOYER LAND AND CATTLECAFO · 3.4 mi
- HEITSTUMAN RANCH COMPANY (FEEDLOT)CAFO · 3.6 mi
- DELL LUNDER FEEDLOTCAFO · 3.7 mi
- G BERT HENRIKSONUnderground Storage Tanks · 4.1 mi
- VAN BUREN, DONALD - DONALD VAN BUREN FEEDLOTCAFO · 4.5 mi
- NEZ PERCE YOUNG HORSEMAN PROJECTCAFO · 4.5 mi
- RICHARD W. WAGNERUnderground Storage Tanks · 4.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Sweetwater'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 Sweetwater.
Total Sites
133
within ~10 miles of Sweetwater
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Sweetwater
Severity Distribution
within ~10 miles of Sweetwater
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Sweetwater, CAFO runs higher than the national average — 11 sites within ~10 miles of Sweetwater. 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.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in Sweetwater
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 Sweetwater average
Your land is one point inside Sweetwater
Everything above resolves to Sweetwater as a whole — one PHZM band and one 28°F frost record, read across 763 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 Sweetwater Average
Sweetwater Average
- ●USDA Zones 7b, averaged across Sweetwater
- ●One soil character for all of Sweetwater
- ●Frost dates read at Sweetwater's scale: Mar 16 to Nov 12
YOUR Parcel
- ✓Your exact zone, not Sweetwater's 7b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Sweetwater
Pull a site-specific report for your exact address in Sweetwater, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sweetwater averages can't show:
We read public map data around Sweetwater — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sweetwater average
How we know this about Sweetwater
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 Sweetwater’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 Sweetwater
When does frost risk typically end in Sweetwater?
The last hard freeze (28°F) in Sweetwater typically lands around Mar 16, 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 6.
When is the first frost in Sweetwater?
The first hard freeze (28°F) in Sweetwater typically arrives around Nov 12, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 29, so the watching starts about Oct 13 — about 241 days after the spring freeze cleared.
How long is the growing season in Sweetwater?
Measured between 28°F hard freezes, Sweetwater sees about 241 frost-free days — roughly Mar 16 through Nov 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 6 to Oct 29, about 206 days.
Is the soil safe to grow vegetables in Sweetwater?
The federal record around Sweetwater is a meaningful one — 133 documented sites, mostly Underground Storage Tanks entries (62), the nearest Nitrate record about 0.3 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.
How do I protect my plants from frost in Sweetwater?
From about Oct 13 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 12 (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 12. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Sweetwater's scale — its 7b band and its 241-day season. Your yard writes its own version of Sweetwater'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 Sweetwater’s own scale
6 of the readings below were taken at Sweetwater's own scale — its own ~241-day season between 28°F freezes, the 763 acres it covers and 133 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Sweetwater's own USDA hardiness band, zones 7bUSDA PHZM 2023
- Sweetwater's own 28°F hard-freeze dates, about Mar 16 and Nov 12 and the ~241-day span between themNOAA 1991–2020 Climate Normals
- 133 documented contamination sites on the federal record near Sweetwater, the closest Nitrate record about 0.3 miles out from the town centreFederal environmental registers
- Sweetwater's boundary and the 763 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7b and a ~241-day seasonGrowable Ground crop-matching engine
- The ecoregion at Sweetwater's own centroid, the Columbia PlateauUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Sweetwater's 763 acres read through its county's SSURGO summaryfrom Nez Perce County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Nez Perce County
- The growing challenges every Idaho grower plans around — written at state scale, so they stay on the state guidefrom Idaho
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Nez Perce County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Sweetwater's 763 acreswhy one lot differs from the next →
- Which side of Sweetwater you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 763 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.3 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 Sweetwater-wide figureread your own land →
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