The California Central Valley spans USDA hardiness zones 9a-9b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
A vast flat alluvial trough with hot dry summers and rich soils — one of the most productive agricultural regions on earth, from almonds and stone fruit to row crops. Growers here do well with tomato, artichoke, fig, and california poppy — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
The California Central Valley spans California. Its footprint follows the EPA Level III ecoregion boundary; the counties linked below are representative of the region, not an exhaustive list.
Your yard isn't all of the California Central Valley.
The California Central Valley spans USDA zones 9a-9b, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 California Central Valley — soil, climate, flood, and parcel records. How we handle your address.
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The California Central Valley — the short answer
The California Central Valley: USDA zones 9a-9b, 318–334 frost-free days, in California.
- USDA zones
- 9a-9b
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 318–334 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Counties
- 11
- US Census TIGER/Line 2025
- Region type
- EPA ecoregion
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in the California Central Valley
Plants matched to the California Central Valley's USDA zones 9a-9b, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the California Central Valley
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the California Central Valley’s USDA zones 9a-9b — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the California Central Valley
The USDA soil survey maps this ground county by county. These are those records weighted by land area across eleven member counties — this region’s own profile, not a state figure.
The ground is predominantly Entisols, at 24% of mapped acres, followed by Alfisols (23%), Mollisols (20%) and Inceptisols (17%). Nine soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Cajon, Toomes, and Newville.
60% of those acres are well drained, and another 9% moderately well drained, 9% somewhat excessively drained. Topsoil pH runs 5.8–8.3 between the lowest and the highest county on record.
Soil order
Entisols
Drainage
Well drained
Topsoil pH
5.8–8.3
Hydric soils
13%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Sutter County holds the most wetland ground here, at 50% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the California Central Valley
The soil survey reads this ground county by county, and the readings above are those records summed across the California Central Valley. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records60% of the mapped acres across the California Central Valley are well drained — ground that drains quickly. That is area-weighted across all eleven of its mapped counties.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
From county recordsTopsoil across the California Central Valley runs pH 5.8–8.3 — near neutral in nine of its eleven counties.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Safe to Grow Here?
What the federal record shows across the California Central Valley — and how to grow with it.
Across the California Central Valley's 11 counties the federal record holds 38,892 documented sites, mostly Brownfields (25,897), Nitrate (9,258) and Underground Storage Tanks (2,145). The heaviest single county is Kern County, with 8,118.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the California Central Valley to see which records sit where you actually grow.
Sources Checked
Summed across the 11 counties in the California Central Valley
A note from Gnorman
What an experienced grower watches for around here
In and around the California Central Valley, Brownfields runs higher than the national average — 25,897 sites across the 11 counties in the California Central Valley. 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.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the California Central Valley
Everything above resolves to the California Central Valley as a whole — a footprint spanning USDA zones 9a-9b. Your parcel sits in exactly one of them. 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 region 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 regional average.
Your Lot vs the California Central Valley Average
California Central Valley Average
- ●USDA Zones 9a-9b, averaged across California Central Valley
- ●One soil character for all of California Central Valley
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not California Central Valley's 9a-9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the California Central Valley
Pull a site-specific report for your exact address in the California Central Valley — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that California Central Valley averages can't show:
We read public map data around The California Central Valley — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the California Central Valley average
How we know this about the California Central Valley
The boundary: an EPA Level III ecoregion (an area sharing climate, soils, and vegetation). Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the California Central Valley
What hardiness zone is the California Central Valley?
The California Central Valley spans USDA hardiness zones 9a-9b, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the California Central Valley?
Measured between 28°F hard freezes, the California Central Valley's counties mostly run 322 to 329 frost-free days, median 324 (NOAA Regional Climate Centers ACIS, 1991–2020, over 11 member counties). That 7-day spread is the honest read — no single season describes 11 counties, and each county guide below carries its own.
When does frost risk end in the California Central Valley?
Across the California Central Valley, the middle half of member counties see their last 28°F hard freeze between Jan 17 and Jan 22 (median Jan 21), and their first fall freeze between Dec 9 and Dec 13. Those are hard freezes, not the last light frost: tender transplants wait for about Feb 11, and elevation decides which end of a 5-day spread you garden in.
What grows well in the California Central Valley?
The California Central Valley's conditions suit plants such as Tomato, Artichoke, Fig, California Poppy, Rosemary, Olive. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the California Central Valley defined?
The California Central Valley's footprint follows an EPA Level III ecoregion — a boundary drawn where climate, soils, and vegetation actually change rather than where a state line falls. It covers 11 counties, and the counties linked on this page are representative of the region, not an exhaustive list.
Which states does the California Central Valley cover?
The California Central Valley spans California. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Pacific Northwest, Sacramento Valley, San Joaquin Valley, Sierra Nevada Foothills, Sonoran Desert, and California Delta share at least one state with the California Central Valley. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the California Central Valley’s own scale
6 of the readings below were taken at the California Central Valley's own scale — the zone 9a-9b band across its footprint, a median 324-day season across its 11 counties and 38,892 documented federal contamination records across its 11 counties, 8,118 of them in Kern County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 9a-9b aggregated across all 11 counties in the footprintUSDA PHZM 2023
- The boundary itself — the EPA Level III ecoregion its 11 counties sit inside, drawn where climate and soils changeEPA Level III Ecoregions
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 11 counties run 322 to 329 frost-free days, median 324NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 38,892 documented federal contamination records across its 11 counties, 8,118 of them in Kern County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 24% Entisols, topsoil pH 5.8–8.3, area-weighted across its 11 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 9a-9bfrom California
What this page can’t tell you
- Which end of the 7-day range your ground sits at — 322 days at one extreme, 329 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the California Central Valley
State growing guides
Representative counties
Other growing regions across California
The maritime Northwest west of the Cascade crest — mild, wet winters and dry summers behind berries, tree fruit, and lush cool-season gardens. (Union of the west-side ecoregions.)
The cooler, wetter northern half of the Central Valley — rice, walnuts, tomatoes, and orchard fruit on rich alluvial bottomland.
The hot southern half of California's Central Valley — deep soils and intense sun behind almonds, stone fruit, grapes, and row crops at vast scale.
California's Gold Country foothills — rocky, well-drained slopes and warm days that suit wine grapes, olives, and Mediterranean orchard crops.
A warm desert of saguaro and palo verde with mild winters that allow desert citrus, dates, and prickly pear alongside intensive irrigated gardening.
Where the Sacramento and San Joaquin rivers braid into a maze of levee-ringed islands, the afternoon "Delta breeze" draws cool marine air off San Francisco Bay through the Carquinez Strait — tempering the interior valley's heat and stretching the frost-free season past 330 days in the western Delta (Solano and Contra Costa counties, per county_data.json). Behind the levees lie the black organic peat and muck soils of the reclaimed islands, the ground that made this California's historic Bartlett-pear and asparagus country and now grows cool-loving Clarksburg-AVA wine grapes like Chenin Blanc. It is the one corner of the Central Valley where a maritime influence, not just the sun, sets the growing rules.