Clayton, California, sits in USDA hardiness zone 9b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Well-matched crops include okra, meyer lemon, california poppy, and artichoke, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Clayton, 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 Clayton 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 Clayton — soil, climate, flood, and parcel records. How we handle your address.
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Clayton — the short answer
Clayton, California: USDA zone 9b, about 332 days between hard freezes, across 2K acres of city.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 16
- Contra Costa County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 14
- Contra Costa County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~332
- Contra Costa 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 Contra Costa County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9b is Clayton's average, not your lot's — a low corner or a tree line moves it. Against Clayton's 332-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Clayton
Each reading below is measured for Clayton itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsClayton runs about 332 days between hard freezes (read from Contra Costa County, the closest normal to Clayton) — 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
MeasuredClayton 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 Clayton is in
Clayton sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Clayton's own centroid rather than borrowed from Contra Costa County.
What Grows in Clayton
Every plant below cleared Clayton's own zone 9b and its 332-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Clayton?
For most of the year, no — what changes is which crops still fit the days remaining. 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 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 14 — long-season crops need about 90 days of runway, quick greens only 30. In a climate this gentle, “too late” hardly applies — the question becomes which crops prefer the cooler months ahead.
Documented around Clayton
Spotted lanternfly documented 21 miles from Clayton, first recorded 2023. What to watch for.
What's on the federal record near Clayton
Closest first, within ~10 miles of Clayton. Listing isn't leaking, and distance isn't exposure.
- CVS PHARMACY #6526Brownfields · 800 ft
- AT&T California - W1202Underground Storage Tanks · 1100 ft
- PACIFIC BELLBrownfields · 1100 ft
- AMERICAN GOLF CORP DBA OAKHURST COUNTRY CLUBBrownfields · 2200 ft
- SEVEN UP BOTTLING COBrownfields · 2300 ft
- CITY OF CLAYTONBrownfields · 0.5 mi
- SHUCK, NICHOLASBrownfields · 0.6 mi
- CALIFORNIA STATE PARKS MOUNT DIABLO SPBrownfields · 0.6 mi
- MIKE AIELLOBrownfields · 0.6 mi
- MICHAEL SIBBITTBrownfields · 0.8 mi
- DIABLO VIEW MIDDLE SCHOOLBrownfields · 0.8 mi
- 1211 AMARANTH WAYBrownfields · 0.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Clayton'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 Clayton.
Sources Checked
within ~10 miles of Clayton
Severity Distribution
within ~10 miles of Clayton
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Clayton, Brownfields runs higher than the national average — 2,624 sites within ~10 miles of Clayton. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Clayton
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 Clayton average
Your land is one point inside Clayton
Everything above resolves to Clayton as a whole — one PHZM band, read across 2K acres, with hard-freeze dates borrowed from Contra Costa 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 Clayton Average
Clayton Average
- ●USDA Zones 9b, averaged across Clayton
- ●One soil character for all of Clayton
- ●Frost dates read at Clayton's scale: Jan 16 to Dec 14
YOUR Parcel
- ✓Your exact zone, not Clayton's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Clayton
Pull a site-specific report for your exact address in Clayton, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Clayton averages can't show:
We read public map data around Clayton — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Clayton average
How we know this about Clayton
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 Contra Costa 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 Clayton
When does frost risk typically end in Clayton?
The last hard freeze (28°F) in Clayton typically lands around Jan 16, 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 6.
When is the first frost in Clayton?
The first hard freeze (28°F) in Clayton typically arrives around Dec 14, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 30, so the watching starts about Nov 14 — about 332 days after the spring freeze cleared.
How long is the growing season in Clayton?
Measured between 28°F hard freezes, Clayton sees about 332 frost-free days — roughly Jan 16 through Dec 14, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 6 to Nov 30, about 297 days.
Is the soil safe to grow vegetables in Clayton?
The federal record around Clayton is a meaningful one — 2,941 documented sites, mostly Brownfields entries (2,624), the nearest Brownfields record about 0.2 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Clayton?
From about Nov 14 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 14 (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 14. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Clayton's scale — its 9b band and its 332-day season. Your yard writes its own version of Clayton'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 Clayton’s own scale
6 of the readings below were taken at Clayton's own scale — the 2,458 acres it covers and 2,941 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Clayton's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 2,941 documented contamination sites on the federal record near Clayton, the closest Brownfields record about 0.2 miles out from the town centreFederal environmental registers
- Clayton's boundary and the 2,458 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~332-day seasonGrowable Ground crop-matching engine
- The ecoregion at Clayton's own centroid, the Central California Foothills and Coastal MountainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Claytonlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Clayton has no normal of its own, so its county's is the closest measured readfrom Contra Costa County
- Soil character — no town-scale survey exists, so Clayton's 2,458 acres read through its county's SSURGO summaryfrom Contra Costa County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Contra Costa 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 Contra Costa County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Clayton's 2,458 acreswhy one lot differs from the next →
- Which side of Clayton you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,458 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 Clayton-wide figureread your own land →