Alturas, California, 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.
Crops well matched to these conditions include cabbage, blackberry, california poppy, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Alturas, 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 Alturas 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 Alturas — soil, climate, flood, and parcel records. How we handle your address.
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Alturas — the short answer
Alturas, California: USDA zone 6a, about 131 days between hard freezes, across 2K acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 17
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 25
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~131
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 2K 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 Alturas's average, not your lot's — a low corner or a tree line moves it. Against Alturas's 131-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Alturas
Each reading below is measured for Alturas itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredAlturas runs about 131 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredAlturas 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 Alturas is in
Alturas sits in the Eastern Cascades Slopes and Foothills — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Alturas's own centroid rather than borrowed from Modoc County.
What Grows in Alturas
Every plant below cleared Alturas's own zone 6a and its 131-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Alturas?
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 Apr 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 17 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 25 — long-season crops need about 90 days of runway, quick greens only 30. Even here the calendar’s edges hold value: thirty-day greens late in the window, then garlic and a rested bed for spring.
What's on the federal record near Alturas
Closest first, within ~10 miles of Alturas. Listing isn't leaking, and distance isn't exposure.
- DOHS-MODOC COBrownfields · 1100 ft
- ED STAUB & SONS PETROLEUM, INC. - ALTURAS BULK PLANTBrownfields · 1200 ft
- CHARTER COMMUNICATIONS-ALTURASBrownfields · 2000 ft
- BLUE WATER RECYCLING CORPBrownfields · 2100 ft
- SAGE COUNTRY RECYCLING INC DBA SAGE COUNTRY RECYCLINGBrownfields · 2100 ft
- RITE AID 6353Brownfields · 2500 ft
- ALTURAS PITSTOPBrownfields · 2500 ft
- 042N012E11J001MNitrate · 2500 ft
- MODOC UNIF SCH DIST BUS SHOPBrownfields · 2500 ft
- WALTON'S AUTO CAREBrownfields · 2600 ft
- Alturas PitstopUnderground Storage Tanks · 2600 ft
- MARKER OIL COMPANY INC DBA MARKER RV AND POWER SPORTSBrownfields · 0.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Alturas'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 Alturas.
Sources Checked
within ~10 miles of Alturas
Severity Distribution
within ~10 miles of Alturas
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Alturas, Brownfields runs higher than the national average — 31 sites within ~10 miles of Alturas. 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 Alturas
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 Alturas average
Your land is one point inside Alturas
Everything above resolves to Alturas as a whole — one PHZM band and one 28°F frost record, read across 2K 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 Alturas Average
Alturas Average
- ●USDA Zones 6a, averaged across Alturas
- ●One soil character for all of Alturas
- ●Frost dates read at Alturas's scale: May 17 to Sep 25
YOUR Parcel
- ✓Your exact zone, not Alturas's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Alturas
Pull a site-specific report for your exact address in Alturas, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Alturas averages can't show:
We read public map data around Alturas — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Alturas average
How we know this about Alturas
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 Alturas’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 Alturas
When does frost risk typically end in Alturas?
The last hard freeze (28°F) in Alturas typically lands around May 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 Jun 7.
When is the first frost in Alturas?
The first hard freeze (28°F) in Alturas typically arrives around Sep 25, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 11, so the watching starts about Aug 26 — about 131 days after the spring freeze cleared.
How long is the growing season in Alturas?
Measured between 28°F hard freezes, Alturas sees about 131 frost-free days — roughly May 17 through Sep 25, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 7 to Sep 11, about 96 days.
Is the soil safe to grow vegetables in Alturas?
The federal record around Alturas is light — 45 documented sites across the 9 federal source types we checked, mostly Brownfields entries (31), the nearest Brownfields record about 0.2 miles 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 gardeners stretch the season in Alturas?
With about 131 frost-free days between hard freezes, Alturas rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 159 to 187 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 17 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Alturas's scale — its 6a band and its 131-day season. Your yard writes its own version of Alturas'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 Alturas’s own scale
6 of the readings below were taken at Alturas's own scale — its own ~131-day season between 28°F freezes, the 1,817 acres it covers and 45 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Alturas's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Alturas's own 28°F hard-freeze dates, about May 17 and Sep 25 and the ~131-day span between themNOAA 1991–2020 Climate Normals
- 45 documented contamination sites on the federal record near Alturas, the closest Brownfields record about 0.2 miles out from the town centreFederal environmental registers
- Alturas's boundary and the 1,817 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~131-day seasonGrowable Ground crop-matching engine
- The ecoregion at Alturas's own centroid, the Eastern Cascades Slopes and FoothillsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Alturas's 1,817 acres read through its county's SSURGO summaryfrom Modoc County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Modoc 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 Modoc County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Alturas's 1,817 acreswhy one lot differs from the next →
- Which side of Alturas you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,817 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 Alturas-wide figureread your own land →
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