Twain Harte, California, sits in USDA hardiness zone 8b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
These conditions suit cabbage, fig, california poppy, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Twain Harte, 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 Twain Harte 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 Twain Harte — soil, climate, flood, and parcel records. How we handle your address.
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Twain Harte — the short answer
Twain Harte, California: USDA zone 8b, about 249 days between hard freezes, across 2K acres of town.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~249
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town 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 8b is Twain Harte's average, not your lot's — a low corner or a tree line moves it. Against Twain Harte's 249-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Twain Harte
Each reading below is measured for Twain Harte itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredTwain Harte runs about 249 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
MeasuredTwain Harte sits in USDA hardiness zone 8b.
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 Twain Harte is in
Twain Harte sits in the Sierra Nevada — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Twain Harte's own centroid rather than borrowed from Tuolumne County.
What Grows in Twain Harte
Every plant below cleared Twain Harte's own zone 8b and its 249-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Twain Harte?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Feb 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 27 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
What's on the federal record near Twain Harte
Closest first, within ~10 miles of Twain Harte. Listing isn't leaking, and distance isn't exposure.
- Wayne's Twain Harte ShellUnderground Storage Tanks · 900 ft
- TWAIN HARTE FAMILY DENTAL CAREBrownfields · 1500 ft
- TWAIN HARTE VETERINARY HOSPITAL INCBrownfields · 1500 ft
- ROCKYS MOUNTAIN AUTO REPAIRBrownfields · 1700 ft
- PACIFIC BELLBrownfields · 0.5 mi
- BILL SCHNEIDERBrownfields · 0.7 mi
- OVERSTREET PAINTINGBrownfields · 0.7 mi
- TWAIN HARTE COMMUNITY SERVICES DISTBrownfields · 0.7 mi
- JOHN HICKS TRUCKINGBrownfields · 1.0 mi
- SONORA CIRCUITS CORPORATIONBrownfields · 1.4 mi
- Confidence GroupMining · 1.4 mi
- SELBY CABINET SHOPPE INCBrownfields · 1.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Twain Harte'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 Twain Harte.
Total Sites
277
within ~10 miles of Twain Harte
Risk Level
High
Highest-severity
4 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Twain Harte
Severity Distribution
within ~10 miles of Twain Harte
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Twain Harte, two things run higher than the national average within ~10 miles of Twain Harte — Mining (38 sites) and PFAS (4 sites). That's not a problem with your land — it's information about it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in Twain Harte
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 Twain Harte average
Your land is one point inside Twain Harte
Everything above resolves to Twain Harte 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 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 Twain Harte Average
Twain Harte Average
- ●USDA Zones 8b, averaged across Twain Harte
- ●One soil character for all of Twain Harte
- ●Frost dates read at Twain Harte's scale: Mar 23 to Nov 27
YOUR Parcel
- ✓Your exact zone, not Twain Harte's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Twain Harte
Pull a site-specific report for your exact address in Twain Harte, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Twain Harte averages can't show:
We read public map data around Twain Harte — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Twain Harte average
How we know this about Twain Harte
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 Twain Harte’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 Twain Harte
When does frost risk typically end in Twain Harte?
The last hard freeze (28°F) in Twain Harte typically lands around Mar 23, 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 Apr 13.
When is the first frost in Twain Harte?
The first hard freeze (28°F) in Twain Harte typically arrives around Nov 27, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 13, so the watching starts about Oct 28 — about 249 days after the spring freeze cleared.
How long is the growing season in Twain Harte?
Measured between 28°F hard freezes, Twain Harte sees about 249 frost-free days — roughly Mar 23 through Nov 27, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 13 to Nov 13, about 214 days.
Is the soil safe to grow vegetables in Twain Harte?
The federal record around Twain Harte runs heavier than most — 277 documented sites, mostly Brownfields entries (204), the nearest Underground Storage Tanks record about 0.2 miles 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 Twain Harte?
From about Oct 28 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 27 (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 27. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Twain Harte's scale — its 8b band and its 249-day season. Your yard writes its own version of Twain Harte'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 Twain Harte’s own scale
6 of the readings below were taken at Twain Harte's own scale — its own ~249-day season between 28°F freezes, the 2,367 acres it covers and 277 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Twain Harte's own USDA hardiness band, zones 8bUSDA PHZM 2023
- Twain Harte's own 28°F hard-freeze dates, about Mar 23 and Nov 27 and the ~249-day span between themNOAA 1991–2020 Climate Normals
- 277 documented contamination sites on the federal record near Twain Harte, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Twain Harte's boundary and the 2,367 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~249-day seasonGrowable Ground crop-matching engine
- The ecoregion at Twain Harte's own centroid, the Sierra NevadaUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Twain Harte's 2,367 acres read through its county's SSURGO summaryfrom Tuolumne County
- 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 Twain Harte's 2,367 acreswhy one lot differs from the next →
- Which side of Twain Harte you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,367 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks 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 Twain Harte-wide figureread your own land →