Sonora, 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.
Well-matched crops include tomato, artichoke, fig, and california poppy, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Sonora, 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 Sonora 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 Sonora — soil, climate, flood, and parcel records. How we handle your address.
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Sonora — the short answer
Sonora, California: USDA zone 9a, about 183 days between hard freezes, across 2K acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 5
- Tuolumne County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Nov 4
- Tuolumne County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~183
- Tuolumne County normal — NOAA 1991–2020, nearest to this town
- City area
- 2K 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 Tuolumne County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Sonora's average, not your lot's — a low corner or a tree line moves it. Against Sonora's 183-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Sonora
Each reading below is measured for Sonora itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsSonora runs about 183 days between hard freezes (read from Tuolumne County, the closest normal to Sonora) — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSonora 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 Sonora is in
Sonora sits in the Sierra Nevada — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Sonora's own centroid rather than borrowed from Tuolumne County.
What Grows in Sonora
Plants matched to Sonora's USDA zones 9a, ordered by how much hardiness margin each has here — the ones with room to spare at both ends of this town's band lead. Each links to its full growing profile.
Is it too late to plant in Sonora?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Apr 7; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 4 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Sonora
Closest first, within ~10 miles of Sonora. Listing isn't leaking, and distance isn't exposure.
- UNION OIL COMPANY OF CALIFORNIA #0383Brownfields · 200 ft
- UNION OIL COBrownfields · 200 ft
- NUGGETBrownfields · 350 ft
- 7 ELEVEN 37976Brownfields · 350 ft
- VALERO CORNER STORE #3634Brownfields · 400 ft
- 7-ELEVEN INC. STORE# 37976Underground Storage Tanks · 400 ft
- 55 PROPERTIES LLCBrownfields · 450 ft
- Gold Country Gas, dbaUnderground Storage Tanks · 550 ft
- CITY OF SONORA FIRE DEPT.Brownfields · 650 ft
- ADVANCED AUTO REPAIR AND DIESELBrownfields · 750 ft
- PACIFIC BELLBrownfields · 950 ft
- AdministrationUnderground Storage Tanks · 1200 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Sonora'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 Sonora.
Total Sites
442
within ~10 miles of Sonora
Risk Level
High
Highest-severity
6 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Sonora
Severity Distribution
within ~10 miles of Sonora
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Sonora, two things run higher than the national average within ~10 miles of Sonora — Mining (143 sites) and Brownfields (257 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Sonora
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 Sonora average
Your land is one point inside Sonora
Everything above resolves to Sonora as a whole — one PHZM band, read across 2K acres, with hard-freeze dates borrowed from Tuolumne 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 Sonora Average
Sonora Average
- ●USDA Zones 9a, averaged across Sonora
- ●One soil character for all of Sonora
- ●Frost dates read at Sonora's scale: May 5 to Nov 4
YOUR Parcel
- ✓Your exact zone, not Sonora's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Sonora
Pull a site-specific report for your exact address in Sonora, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sonora averages can't show:
We read public map data around Sonora — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sonora average
How we know this about Sonora
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 Tuolumne 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 Sonora
When does frost risk typically end in Sonora?
The last hard freeze (28°F) in Sonora typically lands around May 5, 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 26.
When is the first frost in Sonora?
The first hard freeze (28°F) in Sonora typically arrives around Nov 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 21, so the watching starts about Oct 5 — about 183 days after the spring freeze cleared.
How long is the growing season in Sonora?
Measured between 28°F hard freezes, Sonora sees about 183 frost-free days — roughly May 5 through Nov 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 26 to Oct 21, about 148 days.
Is the soil safe to grow vegetables in Sonora?
The federal record around Sonora runs heavier than most — 442 documented sites, mostly Brownfields entries (257), 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 Sonora?
From about Oct 5 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 Nov 4 (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 Nov 4. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Sonora's scale — its 9a band and its 183-day season. Your yard writes its own version of Sonora'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 Sonora’s own scale
4 of the readings below were taken at Sonora's own scale — the 2,024 acres it covers and 442 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Sonora's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 442 documented contamination sites on the federal record near Sonora, the closest Brownfields record under a tenth of a mile out from the town centreFederal environmental registers
- Sonora's boundary and the 2,024 acres inside itUS Census TIGER/Line 2025
- The ecoregion at Sonora's own centroid, the Sierra NevadaUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Sonora has no normal of its own, so its county's is the closest measured readfrom Tuolumne County
- Soil character — no town-scale survey exists, so Sonora's 2,024 acres read through its county's SSURGO summaryfrom Tuolumne County
- The candidate plant list — California's curated set, filtered to this zone band and re-ordered by how much margin each has herefrom California
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Tuolumne 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 Tuolumne County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Sonora's 2,024 acreswhy one lot differs from the next →
- Which side of Sonora you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,024 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 Sonora-wide figureread your own land →
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