Hammett, Idaho, 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 Hammett, 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 Hammett 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 Hammett — soil, climate, flood, and parcel records. How we handle your address.
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Hammett — the short answer
Hammett, Idaho: USDA zone 7a, about 191 days between hard freezes, across 752 acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 24
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~191
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 752 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 Hammett's average, not your lot's — a low corner or a tree line moves it. Against Hammett's 191-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Hammett
Each reading below is measured for Hammett itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHammett runs about 191 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredHammett 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 Hammett is in
Hammett sits in the Snake River Plain — EPA Level III, inside the wider North American Deserts. That is read at Hammett's own centroid rather than borrowed from Elmore County.
What Grows in Hammett
Every plant below cleared Hammett's own zone 7a and its 191-day season. Each card opens that plant's Idaho profile. How we score.
Is it too late to plant in Hammett?
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 Mar 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 24 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Hammett
Closest first, within ~10 miles of Hammett. Listing isn't leaking, and distance isn't exposure.
- HAMMETT VALLEY MARKETUnderground Storage Tanks · 600 ft
- CENTENNIAL TRACTORUnderground Storage Tanks · 1300 ft
- 05S 08E 36CBB1Nitrate · 1700 ft
- 06S 08E 01BBA1Nitrate · 0.5 mi
- 05S 08E 36BDD2Nitrate · 0.6 mi
- HAMMETT STATIONUnderground Storage Tanks · 1.1 mi
- 05S 08E 34DBA1Nitrate · 1.3 mi
- 05S 09E 31DBB1Nitrate · 1.8 mi
- HOODCO STORAGESUnderground Storage Tanks · 1.9 mi
- USDOI BLM HAMMETT DUMPSuperfund · 4.1 mi
- 05S 09E 27DBB1Nitrate · 4.9 mi
- NW PIPELINE MOUNTAIN HOME COMPRESSOR STATIONBrownfields · 6.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Hammett'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 Hammett.
Total Sites
52
within ~10 miles of Hammett
Risk Level
Elevated
Highest-severity
4 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Hammett
Severity Distribution
within ~10 miles of Hammett
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Hammett, two things run higher than the national average within ~10 miles of Hammett — Superfund (4 sites) and Nitrate (22 sites). That's not a problem with your land — it's information about it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Hammett
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 Hammett average
Your land is one point inside Hammett
Everything above resolves to Hammett as a whole — one PHZM band and one 28°F frost record, read across 752 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 Hammett Average
Hammett Average
- ●USDA Zones 7a, averaged across Hammett
- ●One soil character for all of Hammett
- ●Frost dates read at Hammett's scale: Apr 16 to Oct 24
YOUR Parcel
- ✓Your exact zone, not Hammett's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Hammett
Pull a site-specific report for your exact address in Hammett, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Hammett averages can't show:
We read public map data around Hammett — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Hammett average
How we know this about Hammett
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 Hammett’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 Hammett
When does frost risk typically end in Hammett?
The last hard freeze (28°F) in Hammett typically lands around Apr 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 May 7.
When is the first frost in Hammett?
The first hard freeze (28°F) in Hammett typically arrives around Oct 24, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 10, so the watching starts about Sep 24 — about 191 days after the spring freeze cleared.
How long is the growing season in Hammett?
Measured between 28°F hard freezes, Hammett sees about 191 frost-free days — roughly Apr 16 through Oct 24, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 7 to Oct 10, about 156 days.
Is the soil safe to grow vegetables in Hammett?
The federal record around Hammett is a meaningful one — 52 documented sites, mostly Underground Storage Tanks entries (23), the nearest Underground Storage Tanks record about 0.1 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.
How do I protect my plants from frost in Hammett?
From about Sep 24 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 24 (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 24. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Hammett's scale — its 7a band and its 191-day season. Your yard writes its own version of Hammett'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 Hammett’s own scale
6 of the readings below were taken at Hammett's own scale — its own ~191-day season between 28°F freezes, the 752 acres it covers and 52 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Hammett's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Hammett's own 28°F hard-freeze dates, about Apr 16 and Oct 24 and the ~191-day span between themNOAA 1991–2020 Climate Normals
- 52 documented contamination sites on the federal record near Hammett, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Hammett's boundary and the 752 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~191-day seasonGrowable Ground crop-matching engine
- The ecoregion at Hammett's own centroid, the Snake River PlainUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Hammett's 752 acres read through its county's SSURGO summaryfrom Elmore County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Elmore 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 Elmore County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Hammett's 752 acreswhy one lot differs from the next →
- Which side of Hammett you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 752 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 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 Hammett-wide figureread your own land →
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