Fort Irwin, California, sits in USDA hardiness zone 9a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
A short list that earns its place here — artichoke, fig, california poppy, and cabbage — with any one site's soil, sun, and drainage making the final cut.
Even in Fort Irwin, 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 Fort Irwin 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 Fort Irwin — soil, climate, flood, and parcel records. How we handle your address.
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Fort Irwin — the short answer
Fort Irwin, California: USDA zone 9a, about 328 days between hard freezes, across 4K acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 18
- San Bernardino County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 12
- San Bernardino County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~328
- San Bernardino County normal — NOAA 1991–2020, nearest to this town
- Town area
- 4K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are San Bernardino County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Fort Irwin's average, not your lot's — a low corner or a tree line moves it. Against Fort Irwin's 328-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Fort Irwin
Each reading below is measured for Fort Irwin itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsFort Irwin runs about 328 days between hard freezes (read from San Bernardino County, the closest normal to Fort Irwin) — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredFort Irwin sits in USDA hardiness zone 9a.
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 Fort Irwin is in
Fort Irwin sits in the Mojave Basin and Range — EPA Level III, inside the wider North American Deserts. That is read at Fort Irwin's own centroid rather than borrowed from San Bernardino County.
What Grows in Fort Irwin
Every plant below cleared Fort Irwin's own zone 9a and its 328-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Fort Irwin?
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 Jan 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jan 18 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 12 — long-season crops need about 90 days of runway, quick greens only 30. With almost year-round growing weather, timing is about heat and rainfall more than frost — some bench is always in play.
What's on the federal record near Fort Irwin
Closest first, within ~10 miles of Fort Irwin. Listing isn't leaking, and distance isn't exposure.
- 013N003E05G002SNitrate · 1400 ft
- 013N003E05G001SNitrate · 1400 ft
- 013N003E04M001SNitrate · 0.5 mi
- 013N003E08B001SNitrate · 0.7 mi
- 014N003E32Q003SNitrate · 0.7 mi
- 013N003E04D002SNitrate · 0.8 mi
- 013N003E04D001SNitrate · 0.8 mi
- 013N003E04D003SNitrate · 0.8 mi
- 014N003E33N001SNitrate · 0.8 mi
- 013N003E04K002SNitrate · 0.8 mi
- 013N003E04K004SNitrate · 0.8 mi
- 013N003E04K003SNitrate · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Fort Irwin'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 Fort Irwin.
Total Sites
282
within ~10 miles of Fort Irwin
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Fort Irwin
Severity Distribution
within ~10 miles of Fort Irwin
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Fort Irwin, Nitrate runs higher than the national average — 268 sites within ~10 miles of Fort Irwin. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Fort Irwin
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 Fort Irwin average
Your land is one point inside Fort Irwin
Everything above resolves to Fort Irwin as a whole — one PHZM band, read across 4K acres, with hard-freeze dates borrowed from San Bernardino County’s record because no 30-year normal resolves at this town’s own centroid. 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 Fort Irwin Average
Fort Irwin Average
- ●USDA Zones 9a, averaged across Fort Irwin
- ●One soil character for all of Fort Irwin
- ●Frost dates read at Fort Irwin's scale: Jan 18 to Dec 12
YOUR Parcel
- ✓Your exact zone, not Fort Irwin's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Fort Irwin
Pull a site-specific report for your exact address in Fort Irwin, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Fort Irwin averages can't show:
We read public map data around Fort Irwin — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Fort Irwin average
How we know this about Fort Irwin
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 San Bernardino County’s record, because none resolves here; 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 Fort Irwin
When does frost risk typically end in Fort Irwin?
The last hard freeze (28°F) in Fort Irwin typically lands around Jan 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 Feb 8.
When is the first frost in Fort Irwin?
The first hard freeze (28°F) in Fort Irwin typically arrives around Dec 12, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 28, so the watching starts about Nov 12 — about 328 days after the spring freeze cleared.
How long is the growing season in Fort Irwin?
Measured between 28°F hard freezes, Fort Irwin sees about 328 frost-free days — roughly Jan 18 through Dec 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 8 to Nov 28, about 293 days.
Is the soil safe to grow vegetables in Fort Irwin?
The federal record around Fort Irwin is a meaningful one — 282 documented sites, mostly Nitrate entries (268), 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 Fort Irwin?
From about Nov 12 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 Dec 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 Dec 12. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Fort Irwin's scale — its 9a band and its 328-day season. Your yard writes its own version of Fort Irwin'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 Fort Irwin’s own scale
5 of the readings below were taken at Fort Irwin's own scale — the 4,458 acres it covers and 282 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Fort Irwin's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 282 documented contamination sites on the federal record near Fort Irwin, the closest Nitrate record about 0.3 miles out from the town centreFederal environmental registers
- Fort Irwin's boundary and the 4,458 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~328-day seasonGrowable Ground crop-matching engine
- The ecoregion at Fort Irwin's own centroid, the Mojave Basin and RangeUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Fort Irwin has no normal of its own, so its county's is the closest measured readfrom San Bernardino County
- Soil character — no town-scale survey exists, so Fort Irwin's 4,458 acres read through its county's SSURGO summaryfrom San Bernardino County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom San Bernardino County
- The growing challenges every California grower plans around — written at state scale, so they stay on the state guidefrom California
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom San Bernardino County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Fort Irwin's 4,458 acreswhy one lot differs from the next →
- Which side of Fort Irwin you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,458 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 Fort Irwin-wide figureread your own land →
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