Douglas Flat, California, sits in USDA hardiness zone 9a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Expect artichoke, fig, california poppy, and cabbage to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Douglas Flat, 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 Douglas Flat 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 Douglas Flat — soil, climate, flood, and parcel records. How we handle your address.
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Douglas Flat — the short answer
Douglas Flat, California: USDA zone 9a, about 290 days between hard freezes, across 438 acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Dec 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~290
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 438 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 9a is Douglas Flat's average, not your lot's — a low corner or a tree line moves it. Against Douglas Flat's 290-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Douglas Flat
Each reading below is measured for Douglas Flat itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDouglas Flat runs about 290 days between hard freezes — 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
MeasuredDouglas Flat 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 Douglas Flat is in
Douglas Flat sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Douglas Flat's own centroid rather than borrowed from Calaveras County.
What Grows in Douglas Flat
Every plant below cleared Douglas Flat's own zone 9a and its 290-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Douglas Flat?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Jan 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 20 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 7 — long-season crops need about 90 days of runway, quick greens only 30. With almost year-round growing weather, timing is about heat and rainfall more than frost — some bench is always in play.
What's on the federal record near Douglas Flat
Closest first, within ~10 miles of Douglas Flat. Listing isn't leaking, and distance isn't exposure.
- JOHN KAUTZ FARMSBrownfields · 0.9 mi
- JOSEPH M SENN CONSTRUCTION INCBrownfields · 1.2 mi
- WADE'S HEAVY EQUIPMENT REPAIR INC DBA ADVENTURE HOSE & TRACTOR REPAIRBrownfields · 1.2 mi
- Colonial Energy CE 40137 (formerly Tower Mart #890)Underground Storage Tanks · 1.4 mi
- MOSBAUGH PROPERTIES INCBrownfields · 1.5 mi
- RED HILL SANITARY LANDFILLBrownfields · 1.5 mi
- CCWD - EBBETTS PASSPFAS · 1.6 mi
- PACIFIC BELLBrownfields · 1.6 mi
- Murphys StationUnderground Storage Tanks · 1.6 mi
- KDR ENTERPRISES DBA MURPHYS STATIONBrownfields · 1.6 mi
- KEITH'S AUTOMOTIVE & TIREBrownfields · 1.6 mi
- BILLS AUTO SERVICEBrownfields · 1.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Douglas Flat'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 Douglas Flat.
Total Sites
223
within ~10 miles of Douglas Flat
Risk Level
High
Highest-severity
3 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Douglas Flat
Severity Distribution
within ~10 miles of Douglas Flat
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Douglas Flat, two things run higher than the national average within ~10 miles of Douglas Flat — Mining (56 sites) and PFAS (3 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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 Douglas Flat
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 Douglas Flat average
Your land is one point inside Douglas Flat
Everything above resolves to Douglas Flat as a whole — one PHZM band and one 28°F frost record, read across 438 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 Douglas Flat Average
Douglas Flat Average
- ●USDA Zones 9a, averaged across Douglas Flat
- ●One soil character for all of Douglas Flat
- ●Frost dates read at Douglas Flat's scale: Feb 20 to Dec 7
YOUR Parcel
- ✓Your exact zone, not Douglas Flat's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Douglas Flat
Pull a site-specific report for your exact address in Douglas Flat, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Douglas Flat averages can't show:
We read public map data around Douglas Flat — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Douglas Flat average
How we know this about Douglas Flat
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 Douglas Flat’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 Douglas Flat
When does frost risk typically end in Douglas Flat?
The last hard freeze (28°F) in Douglas Flat typically lands around Feb 20, 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 Mar 13.
When is the first frost in Douglas Flat?
The first hard freeze (28°F) in Douglas Flat typically arrives around Dec 7, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 23, so the watching starts about Nov 7 — about 290 days after the spring freeze cleared.
How long is the growing season in Douglas Flat?
Measured between 28°F hard freezes, Douglas Flat sees about 290 frost-free days — roughly Feb 20 through Dec 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 13 to Nov 23, about 255 days.
Is the soil safe to grow vegetables in Douglas Flat?
The federal record around Douglas Flat runs heavier than most — 223 documented sites, mostly Brownfields entries (140), the nearest Brownfields record about 0.9 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 Douglas Flat?
From about Nov 7 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 7 (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 7. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Douglas Flat's scale — its 9a band and its 290-day season. Your yard writes its own version of Douglas Flat'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 Douglas Flat’s own scale
6 of the readings below were taken at Douglas Flat's own scale — its own ~290-day season between 28°F freezes, the 438 acres it covers and 223 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Douglas Flat's own USDA hardiness band, zones 9aUSDA PHZM 2023
- Douglas Flat's own 28°F hard-freeze dates, about Feb 20 and Dec 7 and the ~290-day span between themNOAA 1991–2020 Climate Normals
- 223 documented contamination sites on the federal record near Douglas Flat, the closest Brownfields record about 0.9 miles out from the town centreFederal environmental registers
- Douglas Flat's boundary and the 438 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~290-day seasonGrowable Ground crop-matching engine
- The ecoregion at Douglas Flat's own centroid, the Central California Foothills and Coastal MountainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Douglas Flat's 438 acres read through its county's SSURGO summaryfrom Calaveras County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Calaveras 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 Calaveras County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Douglas Flat's 438 acreswhy one lot differs from the next →
- Which side of Douglas Flat you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 438 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.9 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 Douglas Flat-wide figureread your own land →
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