Los Altos, California, sits in USDA hardiness zone 9b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Among the crops suited to this profile: okra, meyer lemon, california poppy, and artichoke. The site-level story — soil, sun, drainage — decides the rest.
Even in Los Altos, 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 Altos 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 Altos — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Los Altos — the short answer
Los Altos, California: USDA zone 9b, about 331 days between hard freezes, across 4K acres of city.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 17
- Santa Clara County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 14
- Santa Clara County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~331
- Santa Clara County normal — NOAA 1991–2020, nearest to this town
- City 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 Santa Clara County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9b is Los Altos's average, not your lot's — a low corner or a tree line moves it. Against Los Altos's 331-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Los Altos
Each reading below is measured for Los Altos itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsLos Altos runs about 331 days between hard freezes (read from Santa Clara County, the closest normal to Los Altos) — 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 Altos sits in USDA hardiness zone 9b.
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 Altos is in
Los Altos sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Los Altos's own centroid rather than borrowed from Santa Clara County.
What Grows in Los Altos
Every plant below cleared Los Altos's own zone 9b and its 331-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Los Altos?
Usually not — gardeners here simply switch what goes in the ground as the season moves. 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 17 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 14 — long-season crops need about 90 days of runway, quick greens only 30. And with a calendar this mild, the honest answer is that planting barely stops — winter opens seasons colder regions never see.
Documented around Los Altos
Spotted lanternfly documented 27 miles from Los Altos, first recorded 2023. What to watch for.
What's on the federal record near Los Altos
Closest first, within ~10 miles of Los Altos. Listing isn't leaking, and distance isn't exposure.
- MCKINLEY, GEOFFBrownfields · 150 ft
- 661 COVINGTON RDBrownfields · 1200 ft
- JULIE PONONTINBrownfields · 1400 ft
- GREGG COURANDBrownfields · 1600 ft
- IVANA PANONTINBrownfields · 1600 ft
- MICHELE BIELAKBrownfields · 1900 ft
- HYEUN-SUBrownfields · 1900 ft
- SEBASTIAN KANTHAKBrownfields · 2000 ft
- GEOFF & KAREN MCKINLEYBrownfields · 2000 ft
- JOAN CORDESBrownfields · 2100 ft
- MASY MAFIBrownfields · 2200 ft
- GARY MILESBrownfields · 2300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Los Altos'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 Altos.
Sources Checked
within ~10 miles of Los Altos
Severity Distribution
within ~10 miles of Los Altos
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Los Altos, Brownfields runs higher than the national average — 5,975 sites within ~10 miles of Los Altos. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Los Altos
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 Altos average
Your land is one point inside Los Altos
Everything above resolves to Los Altos as a whole — one PHZM band, read across 4K acres, with hard-freeze dates borrowed from Santa Clara County’s record because no 30-year normal resolves at this city’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 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 Los Altos Average
Los Altos Average
- ●USDA Zones 9b, averaged across Los Altos
- ●One soil character for all of Los Altos
- ●Frost dates read at Los Altos's scale: Jan 17 to Dec 14
YOUR Parcel
- ✓Your exact zone, not Los Altos's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Los Altos
Pull a site-specific report for your exact address in Los Altos, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Los Altos averages can't show:
We read public map data around Los Altos — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Los Altos average
How we know this about Los Altos
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 Santa Clara 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 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 Los Altos
When does frost risk typically end in Los Altos?
The last hard freeze (28°F) in Los Altos typically lands around Jan 17, 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 7.
When is the first frost in Los Altos?
The first hard freeze (28°F) in Los Altos typically arrives around Dec 14, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 30, so the watching starts about Nov 14 — about 331 days after the spring freeze cleared.
How long is the growing season in Los Altos?
Measured between 28°F hard freezes, Los Altos sees about 331 frost-free days — roughly Jan 17 through Dec 14, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 7 to Nov 30, about 296 days.
Is the soil safe to grow vegetables in Los Altos?
The federal record around Los Altos runs heavier than most — 6,734 documented sites, mostly Brownfields entries (5,975), the nearest Brownfields record under a tenth of a mile out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Los Altos?
From about Nov 14 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 14 (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 14. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Los Altos's scale — its 9b band and its 331-day season. Your yard writes its own version of Los Altos'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 Altos’s own scale
6 of the readings below were taken at Los Altos's own scale — the 4,186 acres it covers and 6,734 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Los Altos's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 6,734 documented contamination sites on the federal record near Los Altos, the closest Brownfields record under a tenth of a mile out from the town centreFederal environmental registers
- Los Altos's boundary and the 4,186 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~331-day seasonGrowable Ground crop-matching engine
- The ecoregion at Los Altos's own centroid, the Central California Foothills and Coastal MountainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Los Altoslydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Los Altos has no normal of its own, so its county's is the closest measured readfrom Santa Clara County
- Soil character — no town-scale survey exists, so Los Altos's 4,186 acres read through its county's SSURGO summaryfrom Santa Clara County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Santa Clara 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 Clara County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Los Altos's 4,186 acreswhy one lot differs from the next →
- Which side of Los Altos you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,186 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields 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 Los Altos-wide figureread your own land →