Palo Alto, California, sits in USDA hardiness zone 9b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Expect okra, meyer lemon, california poppy, and artichoke to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Palo Alto, 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 Palo Alto 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 Palo Alto — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Palo Alto — the short answer
Palo Alto, California: USDA zone 9b, about 331 days between hard freezes, across 15K acres of city.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 17
- Santa Clara County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 14
- Santa Clara County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~331
- Santa Clara County normal — NOAA 1991–2020, nearest to this town
- City area
- 15K 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 Santa Clara County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9b is Palo Alto's average, not your lot's — a low corner or a tree line moves it. Against Palo Alto's 331-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Palo Alto
Each reading below is measured for Palo Alto itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsPalo Alto runs about 331 days between hard freezes (read from Santa Clara County, the closest normal to Palo Alto) — 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
MeasuredPalo Alto 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 Palo Alto is in
Palo Alto sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Palo Alto's own centroid rather than borrowed from Santa Clara County.
What Grows in Palo Alto
Every plant below cleared Palo Alto's own zone 9b and its 331-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Palo Alto?
Almost never — the real question is what to plant next. 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 17 (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 Palo Alto
Spotted lanternfly documented 25 miles from Palo Alto, first recorded 2023. What to watch for.
What's on the federal record near Palo Alto
Closest first, within ~10 miles of Palo Alto. Listing isn't leaking, and distance isn't exposure.
- SYNTEX USA INC.Toxics Release Inventory · 300 ft
- NANI LITHOGRAPHY, INC.Brownfields · 350 ft
- VMWARE- CREEKSIDE FUnderground Storage Tanks · 600 ft
- SYNTEX U S A INCBrownfields · 1000 ft
- STANFORD UNIVERSITY AT ARASTRADERO ROADBrownfields · 1100 ft
- DPIX LLCToxics Release Inventory · 1800 ft
- DPIX LLCBrownfields · 1800 ft
- THE BOT LELAND STANFORD JR UNIVERSITYBrownfields · 1800 ft
- TESLA MOTORS, INCBrownfields · 1900 ft
- OREAD INCBrownfields · 1900 ft
- THE BOT LELAND STANFORD JR. UNIVERSITYBrownfields · 2000 ft
- VA PALO ALTO HEALTH CARE SYSTEM - BLDG MEUnderground Storage Tanks · 2100 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Palo Alto'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 Palo Alto.
Sources Checked
within ~10 miles of Palo Alto
Severity Distribution
within ~10 miles of Palo Alto
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Palo Alto, Brownfields runs higher than the national average — 4,824 sites within ~10 miles of Palo Alto. 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 Palo Alto
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 Palo Alto average
Your land is one point inside Palo Alto
Everything above resolves to Palo Alto as a whole — one PHZM band, read across 15K acres, with hard-freeze dates borrowed from Santa Clara 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 Palo Alto Average
Palo Alto Average
- ●USDA Zones 9b, averaged across Palo Alto
- ●One soil character for all of Palo Alto
- ●Frost dates read at Palo Alto's scale: Jan 17 to Dec 14
YOUR Parcel
- ✓Your exact zone, not Palo Alto's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Palo Alto
Pull a site-specific report for your exact address in Palo Alto, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Palo Alto averages can't show:
We read public map data around Palo Alto — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Palo Alto average
How we know this about Palo Alto
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 Santa Clara 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 Palo Alto
When does frost risk typically end in Palo Alto?
The last hard freeze (28°F) in Palo Alto typically lands around Jan 17, 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 7.
When is the first frost in Palo Alto?
The first hard freeze (28°F) in Palo Alto 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 331 days after the spring freeze cleared.
How long is the growing season in Palo Alto?
Measured between 28°F hard freezes, Palo Alto sees about 331 frost-free days — roughly Jan 17 through Dec 14, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 7 to Nov 30, about 296 days.
Is the soil safe to grow vegetables in Palo Alto?
The federal record around Palo Alto runs heavier than most — 5,444 documented sites, mostly Brownfields entries (4,824), the nearest Toxics Release Inventory record under a tenth of a mile 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 Palo Alto?
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 Palo Alto's scale — its 9b band and its 331-day season. Your yard writes its own version of Palo Alto'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 Palo Alto’s own scale
6 of the readings below were taken at Palo Alto's own scale — the 15,393 acres it covers and 5,444 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Palo Alto's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 5,444 documented contamination sites on the federal record near Palo Alto, the closest Toxics Release Inventory record under a tenth of a mile out from the town centreFederal environmental registers
- Palo Alto's boundary and the 15,393 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~331-day seasonGrowable Ground crop-matching engine
- The ecoregion at Palo Alto's own centroid, the Central California Foothills and Coastal MountainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Palo Altolydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Palo Alto has no normal of its own, so its county's is the closest measured readfrom Santa Clara County
- Soil character — no town-scale survey exists, so Palo Alto's 15,393 acres read through its county's SSURGO summaryfrom Santa Clara County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Santa Clara 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 Santa Clara County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Palo Alto's 15,393 acreswhy one lot differs from the next →
- Which side of Palo Alto you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 15,393 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Toxics Release Inventory 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 Palo Alto-wide figureread your own land →