Los Alamos County, in New Mexico, sits in USDA hardiness zone 7a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
On paper, cabbage, pawpaw, california poppy, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Los Alamos County holds more than one microclimate.
Soils and elevations shift across Los Alamos County, so your frost dates and drainage aren't the county average. 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 County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Los Alamos County — the short answer
Los Alamos County, New Mexico: USDA zone 7a, about 203 days between hard freezes, across 70K acres.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 10
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 30
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~203
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 70K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 Los Alamos County's average, not your lot's — a low corner or a tree line moves it. Against Los Alamos County's 203-day season, see what your own ground reads.
Heat in Los Alamos County
Across a year, Los Alamos County accumulates about 2,249 growing degree days above 50°F, about 924 fewer than the middle New Mexico county — ahead of 6 of New Mexico’s 33 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Los Alamos County
Across Los Alamos County, the ground is predominantly Alfisols, where Carjo, Totavi, and Hackroy are the most extensive named soil series. The soil is generally well drained with a bedrock surface. Topsoil pH runs about 7.0, neutral. Rainfall drains through hydrologic group D soils.
Soil order
Alfisols
Drainage
Well drained
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Los Alamos County
The USDA soil survey maps 51% of Los Alamos County as well drained — but another 9% drains differently: 9% somewhat excessively drained.
Carjo is the most extensive named soil at 26% of mapped acres, then Totavi (14%) and Hackroy (10%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Los Alamos County
Each reading below is measured for Los Alamos County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Los Alamos County are well drained, in hydrologic group D — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Los Alamos County runs about pH 7.0, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Season length
MeasuredLos Alamos County runs about 203 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
MeasuredLos Alamos County 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 Los Alamos County is in
Los Alamos County sits in the Southern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. One consistent ecological setting across the whole county.
What Grows in Los Alamos County
We scored all 1,086 plants against Los Alamos County's own USDA zone 7a and its own 203-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's New Mexico profile.
Is it too late to plant in Los Alamos County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 13; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 10 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 30 — 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.
Documented around Los Alamos County
Survey cells within 31 miles of Los Alamos County checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 421 miles off. What to watch for.
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Los Alamos County
USGS estimates 1,749 lb of Dicamba on Los Alamos County farmland in 2019, its largest by weight, ahead of Triclopyr (699 lb) and Glyphosate (175 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Los Alamos County — and how to grow with it.
We checked the federal record across Los Alamos County — 165 documented sites across 6 of the 9 source types we track.
The most significant on record: 1 Superfund site (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Los Alamos County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Los Alamos County
Closest first, across Los Alamos County. Listing isn't leaking, and distance isn't exposure.
- LOS ALAMOS COUNTY LANDFILLUnderground Storage Tanks · 0.7 mi
- LOS ALAMOS NATIONAL LABORATORYBrownfields · 0.7 mi
- LOS ALAMOS NATIONAL LABORATORYSuperfund · 0.7 mi
- LOS ALAMOS NATIONAL LABORATORYToxics Release Inventory · 0.7 mi
- KWIK LUBE LOS ALAMOSUnderground Storage Tanks · 0.7 mi
- GIANT 380Underground Storage Tanks · 0.7 mi
- KWIK LUBE LOS ALAMOSBrownfields · 0.7 mi
- LOS ALAMOS SHELLUnderground Storage Tanks · 0.8 mi
- RAS 62636Underground Storage Tanks · 0.8 mi
- LOS ALAMOS MAINUnderground Storage Tanks · 0.8 mi
- RICH LARRYUnderground Storage Tanks · 0.8 mi
- TECH AREA 3Underground Storage Tanks · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Los Alamos County'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 County.
Total Sites
165
across Los Alamos County
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
across Los Alamos County
Severity Distribution
across Los Alamos County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Los Alamos County
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 County average
Your land is one point inside Los Alamos County
Everything above resolves to Los Alamos County as a whole — one PHZM band and one county frost record, read across 70K 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 county 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 county average.
Your Lot vs the Los Alamos County Average
Los Alamos County Average
- ●USDA Zones 7a, averaged across Los Alamos County
- ●One soil character for all of Los Alamos County
- ●Frost dates read at Los Alamos County's scale: Apr 10 to Oct 30
YOUR Parcel
- ✓Your exact zone, not Los Alamos County's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Los Alamos County
Pull a site-specific report for your exact address in Los Alamos County, New Mexico — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Los Alamos County averages can't show:
We read public map data around Los Alamos County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Los Alamos County average
How we know this about Los Alamos County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Los Alamos County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Los Alamos County
When does frost risk typically end in Los Alamos County?
The last hard freeze (28°F) in Los Alamos County typically lands around Apr 10, 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 1.
How long is the growing season in Los Alamos County?
Measured between 28°F hard freezes, Los Alamos County sees about 203 frost-free days — roughly Apr 10 through Oct 30, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 1 to Oct 16, about 168 days.
Is the soil safe to grow vegetables in Los Alamos County?
The federal record around Los Alamos County is a meaningful one — 165 documented sites, mostly Underground Storage Tanks entries (85), the nearest Underground Storage Tanks record about 0.7 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.
Everything above is measured at Los Alamos County's scale — its 7a band and its 203-day season. Your yard writes its own version of Los Alamos County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads New Mexico's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Los Alamos County’s own scale
9 of the readings below were taken at Los Alamos County's own scale — its own ~203-day span between 28°F freezes, the 3 most extensive soil series mapped here and 165 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Los Alamos County's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Los Alamos County's own 28°F hard-freeze dates and its ~203-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Los Alamos CountyUSDA NRCS SSURGO
- 165 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.7 miles outFederal environmental registers
- Los Alamos County's boundary and the 69,839 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~203-day seasonGrowable Ground crop-matching engine
- Los Alamos County sitting wholly inside the Southern RockiesUS EPA Level III Ecoregions
- Open occurrence records documented in Los Alamos County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Los Alamos County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every New Mexico grower plans around — written at state scale, so they stay on the state guidefrom New Mexico
What this page can’t tell you
- How the season shifts across Los Alamos County — the ~203 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Los Alamos County's 69,839 acreswhy one lot differs from the next →
- Which of those 165 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Los Alamos Countyread your own land →