Los Alamos, California, sits in USDA hardiness zone 9a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Growers here do well with artichoke, fig, california poppy, and cabbage — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Los Alamos, 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 Los Alamos 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 Los Alamos — soil, climate, flood, and parcel records. How we handle your address.
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Los Alamos — the short answer
Los Alamos, California: USDA zone 9a, about 312 days between hard freezes, across 579 acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Dec 11
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~312
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 579 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 9a is Los Alamos's average, not your lot's — a low corner or a tree line moves it. Against Los Alamos's 312-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Los Alamos
Each reading below is measured for Los Alamos itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredLos Alamos runs about 312 days between hard freezes — 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
MeasuredLos Alamos 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 Los Alamos is in
Los Alamos sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Los Alamos's own centroid rather than borrowed from Santa Barbara County.
What Grows in Los Alamos
Every plant below cleared Los Alamos's own zone 9a and its 312-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Los Alamos?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Jan 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 2 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 11 — long-season crops need about 90 days of runway, quick greens only 30. Here the calendar nearly circles: cool-season crops take the winter shift, and the next window is always close.
What's on the federal record near Los Alamos
Closest first, within ~10 miles of Los Alamos. Listing isn't leaking, and distance isn't exposure.
- DBA LOS ALAMOS GAS & MARTBrownfields · 850 ft
- LOS ALAMOS GAS & MARTUnderground Storage Tanks · 950 ft
- HEALY & ASSOCIATESBrownfields · 950 ft
- VINO FARMS LLC - SM-1 LOS ALAMOSBrownfields · 950 ft
- 008N032W29L004SNitrate · 1100 ft
- SEAFOOD SPECIALTIESBrownfields · 1200 ft
- 008N032W29L003SNitrate · 1300 ft
- 008N032W29LU05SNitrate · 1300 ft
- WENDELIGHTINGBrownfields · 1900 ft
- 008N032W30H007SNitrate · 2100 ft
- COLLINS MARKETUnderground Storage Tanks · 2300 ft
- COLLINS MARKETBrownfields · 2300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Los Alamos'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 Los Alamos.
Total Sites
338
within ~10 miles of Los Alamos
Risk Level
Elevated
Highest-severity
3 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Los Alamos
Severity Distribution
within ~10 miles of Los Alamos
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Los Alamos, Nitrate runs higher than the national average — 220 sites within ~10 miles of Los Alamos. That's not a problem with your land — it's information about 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 Los Alamos
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 Los Alamos average
Your land is one point inside Los Alamos
Everything above resolves to Los Alamos as a whole — one PHZM band and one 28°F frost record, read across 579 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 Los Alamos Average
Los Alamos Average
- ●USDA Zones 9a, averaged across Los Alamos
- ●One soil character for all of Los Alamos
- ●Frost dates read at Los Alamos's scale: Feb 2 to Dec 11
YOUR Parcel
- ✓Your exact zone, not Los Alamos's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Los Alamos
Pull a site-specific report for your exact address in Los Alamos, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Los Alamos averages can't show:
We read public map data around Los Alamos — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Los Alamos average
How we know this about Los Alamos
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 Los Alamos’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 Los Alamos
When does frost risk typically end in Los Alamos?
The last hard freeze (28°F) in Los Alamos typically lands around Feb 2, 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 23.
When is the first frost in Los Alamos?
The first hard freeze (28°F) in Los Alamos typically arrives around Dec 11, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 27, so the watching starts about Nov 11 — about 312 days after the spring freeze cleared.
How long is the growing season in Los Alamos?
Measured between 28°F hard freezes, Los Alamos sees about 312 frost-free days — roughly Feb 2 through Dec 11, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 23 to Nov 27, about 277 days.
Is the soil safe to grow vegetables in Los Alamos?
The federal record around Los Alamos is a meaningful one — 338 documented sites, mostly Nitrate entries (220), the nearest Brownfields record about 0.2 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 Los Alamos?
From about Nov 11 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 11 (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 11. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Los Alamos's scale — its 9a band and its 312-day season. Your yard writes its own version of Los Alamos'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 Los Alamos’s own scale
6 of the readings below were taken at Los Alamos's own scale — its own ~312-day season between 28°F freezes, the 579 acres it covers and 338 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Los Alamos's own USDA hardiness band, zones 9aUSDA PHZM 2023
- Los Alamos's own 28°F hard-freeze dates, about Feb 2 and Dec 11 and the ~312-day span between themNOAA 1991–2020 Climate Normals
- 338 documented contamination sites on the federal record near Los Alamos, the closest Brownfields record about 0.2 miles out from the town centreFederal environmental registers
- Los Alamos's boundary and the 579 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~312-day seasonGrowable Ground crop-matching engine
- The ecoregion at Los Alamos's own centroid, the Central California Foothills and Coastal MountainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Los Alamos's 579 acres read through its county's SSURGO summaryfrom Santa Barbara County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Santa Barbara 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 Santa Barbara County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Los Alamos's 579 acreswhy one lot differs from the next →
- Which side of Los Alamos you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 579 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields 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 Los Alamos-wide figureread your own land →
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