Foster City, California, sits in USDA hardiness zone 10a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Expect artichoke, meyer lemon, california poppy, and cabbage to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Foster City, 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 Foster City 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 Foster City — soil, climate, flood, and parcel records. How we handle your address.
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Foster City — the short answer
Foster City, California: USDA zone 10a, no 28°F killing freeze on record — the season is year-round, across 2K acres of city.
- USDA zone
- 10a
- USDA PHZM 2023
- Killing freeze
- None on record
- NOAA RCC ACIS 1991–2020, this town’s own record
- City area
- 2K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. The year-round finding is measured — a 30-year record with no 28°F killing freeze in it — never inferred from missing dates.
Hardiness Zone Range
Zone 10a is Foster City's average, not your lot's — a low corner or a tree line moves it. Against Foster City's no killing freeze on record, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Foster City
Each reading below is measured for Foster City itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Winter hardiness
MeasuredFoster City sits in USDA hardiness zone 10a.
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 Foster City is in
Foster City sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Foster City's own centroid, and it is not what its county reads: San Mateo County is mostly Coast Range. The wider page above you is answering a different question about different ground.
What Grows in Foster City
Every plant below cleared Foster City's own zone 10a. Each card opens that plant's California profile. How we score.
Documented around Foster City
Spotted lanternfly documented 13 miles from Foster City, first recorded 2023. What to watch for.
What's on the federal record near Foster City
Closest first, within ~10 miles of Foster City. Listing isn't leaking, and distance isn't exposure.
- FRANK SAUNDERSBrownfields · 450 ft
- STEVE FROLLIBrownfields · 850 ft
- RW ZUKIN BEACHCOMBER APTBrownfields · 1100 ft
- LYDIA LEBRONBrownfields · 1500 ft
- ELLIE MATSUOKABrownfields · 1800 ft
- BOWDITCH MIDDLE SCHOOLBrownfields · 2000 ft
- JENNINE MINUSBrownfields · 2600 ft
- ABHI LADBrownfields · 2600 ft
- TERESA LIUBrownfields · 0.5 mi
- SYD POKBrownfields · 0.6 mi
- CAROL LOCKERBYBrownfields · 0.6 mi
- ANGELA RAKITABrownfields · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Foster City'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 Foster City.
Total Sites
4,615
within ~10 miles of Foster City
Risk Level
Elevated
Highest-severity
12 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Foster City
Severity Distribution
within ~10 miles of Foster City
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Foster City, Brownfields runs higher than the national average — 4,147 sites within ~10 miles of Foster City. That's not a problem with your land — it's information about it.
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 Foster City
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 Foster City average
Your land is one point inside Foster City
Everything above resolves to Foster City as a whole — one PHZM band and one 28°F frost record, read across 2K 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 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 Foster City Average
Foster City Average
- ●USDA Zones 10a, averaged across Foster City
- ●One soil character for all of Foster City
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Foster City's 10a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Foster City
Pull a site-specific report for your exact address in Foster City, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Foster City averages can't show:
We read public map data around Foster City — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Foster City average
How we know this about Foster City
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, with the labelled statewide window where none resolves; 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 Foster City
Is it too late to plant in Foster City?
No — Foster City has no 28°F killing freeze in the 30-year station record, so the growing season is year-round and there is no last-frost date to wait for. Planting is paced by rainfall, heat and daylength instead of by frost: start heat-lovers any month, and time cool-season crops (lettuce, brassicas, peas) for the cooler, wetter half of the year or for higher ground. Succession sowing every few weeks works all year, so the limit is what you can keep watered and harvested, not the calendar.
When does frost risk typically end in Foster City?
It doesn't — Foster City records no 28°F killing freeze at all across the 1991–2020 station record, so there is no spring frost date to plant after. Cold still matters with elevation: the higher you garden, the cooler the nights, and a few tropical crops sulk below about 60°F even where they never freeze.
How long is the growing season in Foster City?
Year-round — the 1991–2020 station record for Foster City contains no 28°F killing freeze, so there is no season to measure between freezes. What paces planting instead is heat, rainfall and daylength: the hottest, wettest stretch is the hard part for cool-season crops, not winter. Elevation is the one real exception — the higher you garden, the colder the nights get.
Is the soil safe to grow vegetables in Foster City?
The federal record around Foster City is a meaningful one — 4,615 documented sites, mostly Brownfields entries (4,147), the nearest Brownfields record under a tenth of a mile 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.
Everything above is measured at Foster City's scale — its 10a band and its no killing freeze on record. Your yard writes its own version of Foster City'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 Foster City’s own scale
7 of the readings below were taken at Foster City's own scale — the 2,424 acres it covers and 4,615 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Foster City's own USDA hardiness band, zones 10aUSDA PHZM 2023
- No 28°F killing freeze in the 30-year station record covering Foster City — a year-round growing seasonNOAA Regional Climate Centers ACIS, 1991-2020
- 4,615 documented contamination sites on the federal record near Foster City, the closest Brownfields record under a tenth of a mile out from the town centreFederal environmental registers
- Foster City's boundary and the 2,424 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear Foster City's hardiness zoneGrowable Ground crop-matching engine
- Foster City sits in the Central California Foothills and Coastal Mountains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Foster Citylydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Foster City's 2,424 acres read through its county's SSURGO summaryfrom San Mateo County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom San Mateo 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 San Mateo County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Foster City's 2,424 acreswhy one lot differs from the next →
- Which side of Foster City you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,424 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record under a tenth of a mile 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 Foster City-wide figureread your own land →