Angwin, California, sits in USDA hardiness zone 9b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Crops well matched to these conditions include okra, meyer lemon, california poppy, and artichoke — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Angwin, 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 Angwin 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 Angwin — soil, climate, flood, and parcel records. How we handle your address.
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Angwin — the short answer
Angwin, California: USDA zone 9b, about 327 days between hard freezes, across 3K acres of town.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 23
- Napa County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 16
- Napa County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~327
- Napa County normal — NOAA 1991–2020, nearest to this town
- Town area
- 3K 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 Napa County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9b is Angwin's average, not your lot's — a low corner or a tree line moves it. Against Angwin's 327-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Angwin
Each reading below is measured for Angwin itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsAngwin runs about 327 days between hard freezes (read from Napa County, the closest normal to Angwin) — 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
MeasuredAngwin 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 Angwin is in
Angwin sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Angwin's own centroid rather than borrowed from Napa County.
What Grows in Angwin
Every plant below cleared Angwin's own zone 9b and its 327-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Angwin?
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 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 16 — 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 Angwin
Closest first, within ~10 miles of Angwin. Listing isn't leaking, and distance isn't exposure.
- RIVERA AUTO REPAIRBrownfields · 0.6 mi
- COLLEGE CHEVRONUnderground Storage Tanks · 0.6 mi
- PETER VANDENHOVEN DDSBrownfields · 0.6 mi
- BACKSTREET HOT RODS LLC DBA ANGWIN AUTO CAREBrownfields · 0.6 mi
- PACIFIC BELLBrownfields · 0.6 mi
- NEAL FAMILY VINEYARDBrownfields · 0.7 mi
- PACIFIC UNION COLLEGEUnderground Storage Tanks · 0.7 mi
- NAPA COUNTY - ENVIRONMENTAL MGMTBrownfields · 0.7 mi
- PACIFIC UNION COLLEGESuperfund · 0.7 mi
- PACIFIC UNION COLLEGEBrownfields · 0.7 mi
- COLLEGE CLEANERSBrownfields · 0.7 mi
- HELMER & SONS, INCBrownfields · 1.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Angwin'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 Angwin.
Total Sites
350
within ~10 miles of Angwin
Risk Level
High
Highest-severity
3 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Angwin
Severity Distribution
within ~10 miles of Angwin
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Angwin, Mining runs higher than the national average — 122 sites within ~10 miles of Angwin. 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.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Angwin
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 Angwin average
Your land is one point inside Angwin
Everything above resolves to Angwin as a whole — one PHZM band, read across 3K acres, with hard-freeze dates borrowed from Napa County’s record because no 30-year normal resolves at this town’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 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 Angwin Average
Angwin Average
- ●USDA Zones 9b, averaged across Angwin
- ●One soil character for all of Angwin
- ●Frost dates read at Angwin's scale: Jan 23 to Dec 16
YOUR Parcel
- ✓Your exact zone, not Angwin's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Angwin
Pull a site-specific report for your exact address in Angwin, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Angwin averages can't show:
We read public map data around Angwin — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Angwin average
How we know this about Angwin
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 Napa 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 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 Angwin
When does frost risk typically end in Angwin?
The last hard freeze (28°F) in Angwin typically lands around Jan 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 Feb 13.
When is the first frost in Angwin?
The first hard freeze (28°F) in Angwin typically arrives around Dec 16, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Dec 2, so the watching starts about Nov 16 — about 327 days after the spring freeze cleared.
How long is the growing season in Angwin?
Measured between 28°F hard freezes, Angwin sees about 327 frost-free days — roughly Jan 23 through Dec 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 13 to Dec 2, about 292 days.
Is the soil safe to grow vegetables in Angwin?
The federal record around Angwin runs heavier than most — 350 documented sites, mostly Brownfields entries (168), the nearest Brownfields record about 0.6 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 Angwin?
From about Nov 16 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 16 (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 16. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Angwin's scale — its 9b band and its 327-day season. Your yard writes its own version of Angwin'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 Angwin’s own scale
5 of the readings below were taken at Angwin's own scale — the 3,091 acres it covers and 350 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Angwin's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 350 documented contamination sites on the federal record near Angwin, the closest Brownfields record about 0.6 miles out from the town centreFederal environmental registers
- Angwin's boundary and the 3,091 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~327-day seasonGrowable Ground crop-matching engine
- The ecoregion at Angwin's own centroid, the Central California Foothills and Coastal MountainsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Angwin has no normal of its own, so its county's is the closest measured readfrom Napa County
- Soil character — no town-scale survey exists, so Angwin's 3,091 acres read through its county's SSURGO summaryfrom Napa County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Napa 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 Napa County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Angwin's 3,091 acreswhy one lot differs from the next →
- Which side of Angwin you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,091 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.6 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 Angwin-wide figureread your own land →
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