Cambridge, Idaho, sits in USDA hardiness zone 6a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
A short list that earns its place here — cabbage, blackberry, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Cambridge, 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 Cambridge 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 Cambridge — soil, climate, flood, and parcel records. How we handle your address.
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Cambridge — the short answer
Cambridge, Idaho: USDA zone 6a, about 180 days between hard freezes, across 310 acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 18
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 15
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~180
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 310 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 6a is Cambridge's average, not your lot's — a low corner or a tree line moves it. Against Cambridge's 180-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Cambridge
Each reading below is measured for Cambridge itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredCambridge runs about 180 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
MeasuredCambridge sits in USDA hardiness zone 6a.
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 Cambridge is in
Cambridge sits in the Snake River Plain — EPA Level III, inside the wider North American Deserts. That is read at Cambridge's own centroid rather than borrowed from Washington County.
What Grows in Cambridge
Every plant below cleared Cambridge's own zone 6a and its 180-day season. Each card opens that plant's Idaho profile. How we score.
Is it too late to plant in Cambridge?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 21; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 18 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 15 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Cambridge
Closest first, within ~10 miles of Cambridge. Listing isn't leaking, and distance isn't exposure.
- Jay's SinclairUnderground Storage Tanks · 300 ft
- HUNTERS INNUnderground Storage Tanks · 350 ft
- 14N 03W 03DDC1Nitrate · 350 ft
- CONSUMERS CO-OPUnderground Storage Tanks · 550 ft
- CAMBRIDGE CHEVRONUnderground Storage Tanks · 750 ft
- CAMBRIDGE CONVENIENCE LLC CIRCLE AUnderground Storage Tanks · 750 ft
- WASHINGTON CO ROAD & BRIDGEUnderground Storage Tanks · 800 ft
- GATEWAY STOREUnderground Storage Tanks · 800 ft
- DEMOSS & SONS (CRAIG DEMOSS)Underground Storage Tanks · 800 ft
- CAMBRIDGE MTCE YARD #3060Underground Storage Tanks · 800 ft
- CAMBRIDGE SCHOOL DISTUnderground Storage Tanks · 1000 ft
- CAMBRIDGE WAREHOUSEUnderground Storage Tanks · 1300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Cambridge'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 Cambridge.
Sources Checked
within ~10 miles of Cambridge
Severity Distribution
within ~10 miles of Cambridge
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Cambridge, Nitrate runs higher than the national average — 30 sites within ~10 miles of Cambridge. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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 Cambridge
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 Cambridge average
Your land is one point inside Cambridge
Everything above resolves to Cambridge as a whole — one PHZM band and one 28°F frost record, read across 310 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 Cambridge Average
Cambridge Average
- ●USDA Zones 6a, averaged across Cambridge
- ●One soil character for all of Cambridge
- ●Frost dates read at Cambridge's scale: Apr 18 to Oct 15
YOUR Parcel
- ✓Your exact zone, not Cambridge's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Cambridge
Pull a site-specific report for your exact address in Cambridge, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Cambridge averages can't show:
We read public map data around Cambridge — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Cambridge average
How we know this about Cambridge
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 Cambridge’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 Cambridge
When does frost risk typically end in Cambridge?
The last hard freeze (28°F) in Cambridge typically lands around Apr 18, 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 9.
When is the first frost in Cambridge?
The first hard freeze (28°F) in Cambridge typically arrives around Oct 15, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 1, so the watching starts about Sep 15 — about 180 days after the spring freeze cleared.
How long is the growing season in Cambridge?
Measured between 28°F hard freezes, Cambridge sees about 180 frost-free days — roughly Apr 18 through Oct 15, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 9 to Oct 1, about 145 days.
Is the soil safe to grow vegetables in Cambridge?
The federal record around Cambridge is light — 49 documented sites across the 9 federal source types we checked, mostly Nitrate entries (30), the nearest Underground Storage Tanks record under a tenth of a mile out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do I protect my plants from frost in Cambridge?
From about Sep 15 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 15 (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 15. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Cambridge's scale — its 6a band and its 180-day season. Your yard writes its own version of Cambridge'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 Cambridge’s own scale
6 of the readings below were taken at Cambridge's own scale — its own ~180-day season between 28°F freezes, the 310 acres it covers and 49 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Cambridge's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Cambridge's own 28°F hard-freeze dates, about Apr 18 and Oct 15 and the ~180-day span between themNOAA 1991–2020 Climate Normals
- 49 documented contamination sites on the federal record near Cambridge, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Cambridge's boundary and the 310 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~180-day seasonGrowable Ground crop-matching engine
- The ecoregion at Cambridge's own centroid, the Snake River PlainUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Cambridge's 310 acres read through its county's SSURGO summaryfrom Washington County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Washington 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 Washington County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Cambridge's 310 acreswhy one lot differs from the next →
- Which side of Cambridge you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 310 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 Cambridge-wide figureread your own land →
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