The San Francisco Bay Area spans USDA hardiness zones 9b-10b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Fog off the Pacific is what sets the Bay Area apart from every other California growing region: the marine layer that grays a July morning also caps summer heat, so cool-season crops that bolt inland — brassicas, lettuces, peas, artichokes, and cane berries — run nearly year-round here, while heat-lovers like tomatoes, peppers, and melons ripen slowly and want the warmest, most sheltered corner of the yard. It's a mild, effectively frost-free maritime band (USDA zones 9b-10b; 331+ frost-free days across Alameda, Marin, and Santa Clara, and no meaningful frost season in San Francisco or on the San Mateo Peninsula) spanning the city, the Peninsula, the East Bay, and the South Bay — a genuinely different climate from the hot-summer Central Valley at the same hardiness zone, and from the warmer North Bay wine valleys just over the hills. Crops well matched to these conditions include tomato, artichoke, avocado, and meyer lemon — though what thrives on any one site still turns on its specific soil, sun, and drainage.
The San Francisco Bay Area spans California.
Your yard isn't all of the San Francisco Bay Area.
The San Francisco Bay Area spans USDA zones 9b-10b, 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 San Francisco Bay Area — soil, climate, flood, and parcel records. How we handle your address.
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The San Francisco Bay Area — the short answer
The San Francisco Bay Area: USDA zones 9b-10b, 331–365 frost-free days depending where in it you stand, in California.
- USDA zones
- 9b-10b
- USDA PHZM 2023, aggregated over the footprint
- Shortest season here
- 331 days
- NOAA Regional Climate Centers ACIS, 1991-2020 — Santa Clara County
- Counties
- 5
- US Census TIGER/Line 2025
- Region type
- County cluster
- 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. The season figure is this region's own record, measured across its 4 member counties, not a state or national average.
Hardiness Zone Range
The San Francisco Bay Area is not one growing season
One answer for the San Francisco Bay Area averages 4 counties whose growing seasons are 34 days apart — from 331 frost-free days in Santa Clara County to 365 in San Mateo County. That is the same region, measured the same way, in the same years. Which end of it your land sits nearer decides what finishes before the first hard freeze.
The middle half of 4 counties runs 333–343 days, with a median of 335 days — a 34-day span end to end.
Measured across 4 member counties, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020. A member with no own record is absent from the range rather than counted as zero — nothing here is interpolated to the region. Your own site sits somewhere inside this range; a parcel report resolves where.
Where the line runs inside the San Francisco Bay Area
The middle half of the San Francisco Bay Area runs 333–343 frost-free days, and 2 of its 4 counties sit outside that — 1 on the short side, 1 on the long. A regional planting date describes the middle well and the ends poorly, which is worth knowing before you follow one.
Under 333 frost-free days
1 county
- Santa Clara County · 331 days
The end of the region that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
333–343 frost-free days
2 counties
0 of 2 shown
The middle half of the region, and the part a single regional season describes well.
Over 343 frost-free days
1 county
- San Mateo County · 365 days
Long enough for a second succession of a quick crop after the first comes out.
Each county is placed by its OWN 28°F frost-free normal (NOAA Regional Climate Centers ACIS, 1991-2020), the same figure its own guide page publishes. Elevation, slope and cold-air drainage move a site within its county as well — which is the part only your address resolves.
What Grows in the San Francisco Bay Area
All 1 of the plants below that publish a season requirement clear even Santa Clara County’s 331 frost-free days — so on season alone, this grid works at both ends of the region. The 34-day spread still decides how far past this list you can push, and how early you can start.
Plants matched to the San Francisco Bay Area's USDA zones 9b-10b, 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 San Francisco Bay Area
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the San Francisco Bay Area’s USDA zones 9b-10b — 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 San Francisco Bay Area
The USDA soil survey maps this ground county by county. These are those records weighted by land area across five member counties — this region’s own profile, not a state figure.
The ground is predominantly Mollisols, at 39% of mapped acres, followed by Entisols (23%), Alfisols (21%) and Inceptisols (9%). Six 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 Gaviota, Vallecitos, and Los Gatos.
60% of those acres are well drained, and another 5% somewhat excessively drained, 5% moderately well drained. Topsoil pH runs 5.8–7.3 between the lowest and the highest county on record.
Soil order
Mollisols
Drainage
Well drained
Topsoil pH
5.8–7.3
Hydric soils
7%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Alameda County holds the most wetland ground here, at 14% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the San Francisco Bay Area
The soil survey reads this ground county by county, and the readings above are those records summed across the San Francisco Bay Area. 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 San Francisco Bay Area are well drained — ground that drains quickly. That is area-weighted across all five 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 San Francisco Bay Area runs pH 5.8–7.3 — near neutral in four of its five 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 San Francisco Bay Area — and how to grow with it.
Across the San Francisco Bay Area's 5 counties the federal record holds 35,085 documented sites, mostly Brownfields (31,202), Underground Storage Tanks (1,741) and Toxics Release Inventory (890). The heaviest single county is Santa Clara County, with 12,058.
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 San Francisco Bay Area to see which records sit where you actually grow.
Sources Checked
Summed across the 5 counties in the San Francisco Bay Area
A note from Gnorman
What an experienced grower watches for around here
In and around the San Francisco Bay Area, Brownfields runs higher than the national average — 31,202 sites across the 5 counties in the San Francisco Bay Area. 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 San Francisco Bay Area
Everything above resolves to the San Francisco Bay Area as a whole — a footprint whose own counties record seasons 34 days apart, and hardiness across zones 9b-10b. Your parcel sits at one point in that range, not in the middle of it. 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 San Francisco Bay Area Average
San Francisco Bay Area Average
- ●USDA Zones 9b-10b, averaged across San Francisco Bay Area
- ●One soil character for all of San Francisco Bay Area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not San Francisco Bay Area's 9b-10b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the San Francisco Bay Area
Pull a site-specific report for your exact address in the San Francisco Bay Area — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that San Francisco Bay Area averages can't show:
We read public map data around The San Francisco Bay Area — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the San Francisco Bay Area average
How we know this about the San Francisco Bay Area
The boundary: a cluster of neighboring counties. 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 San Francisco Bay Area
What hardiness zone is the San Francisco Bay Area?
The San Francisco Bay Area spans USDA hardiness zones 9b-10b, 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 San Francisco Bay Area?
Measured between 28°F hard freezes, the San Francisco Bay Area's counties mostly run 333 to 343 frost-free days, median 335 (NOAA Regional Climate Centers ACIS, 1991–2020, over 5 member counties). That 10-day spread is the honest read — no single season describes 5 counties, and each county guide below carries its own.
When does frost risk end in the San Francisco Bay Area?
Across the San Francisco Bay Area, the middle half of member counties see their last 28°F hard freeze between Jan 11 and Jan 15 (median Jan 12), and their first fall freeze between Dec 12 and Dec 13. Those are hard freezes, not the last light frost: tender transplants wait for about Feb 2, and elevation decides which end of a 4-day spread you garden in.
What grows well in the San Francisco Bay Area?
The San Francisco Bay Area's conditions suit plants such as Tomato, Artichoke, Avocado, Meyer Lemon, Fig, California Poppy. 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 San Francisco Bay Area defined?
The San Francisco Bay Area is defined here as a curated cluster of 5 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the San Francisco Bay Area cover?
The San Francisco Bay Area spans California. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Pacific Northwest, California Central Valley, Sacramento Valley, San Joaquin Valley, Sierra Nevada Foothills, and Sonoran Desert share at least one state with the San Francisco Bay Area. 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 San Francisco Bay Area’s own scale
6 of the readings below were taken at the San Francisco Bay Area's own scale — the zone 9b-10b band across its footprint, a median 335-day season across its 5 counties and 35,085 documented federal contamination records across its 5 counties, 12,058 of them in Santa Clara County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 9b-10b aggregated across all 5 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 5 counties this region is curated fromGrowable Ground subregion registry
- 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 5 counties run 333 to 343 frost-free days, median 335NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 35,085 documented federal contamination records across its 5 counties, 12,058 of them in Santa Clara County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 39% Mollisols, topsoil pH 5.8–7.3, area-weighted across its 5 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 9b-10bfrom California
What this page can’t tell you
- Which end of the 10-day range your ground sits at — 333 days at one extreme, 343 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 San Francisco Bay Area
State growing guides
Counties in this region
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.)
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.
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.