Highgrove, California, sits in USDA hardiness zone 10a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
On paper, avocado, meyer lemon, tomato, and artichoke all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Highgrove, 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 Highgrove 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 Highgrove — soil, climate, flood, and parcel records. How we handle your address.
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Highgrove — the short answer
Highgrove, California: USDA zone 10a, about 303 days between hard freezes, across 2K acres of town.
- USDA zone
- 10a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 13
- Riverside County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 13
- Riverside County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~303
- Riverside County normal — NOAA 1991–2020, nearest to this town
- Town 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 Riverside County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 10a is Highgrove's average, not your lot's — a low corner or a tree line moves it. Against Highgrove's 303-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Highgrove
Each reading below is measured for Highgrove itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsHighgrove runs about 303 days between hard freezes (read from Riverside County, the closest normal to Highgrove) — 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
MeasuredHighgrove 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 Highgrove is in
Highgrove sits in the Southern California/Northern Baja Coast — EPA Level III, inside the wider Mediterranean California. That is read at Highgrove's own centroid, and it is not what its county reads: Riverside County is mostly Sonoran Basin and Range. The wider page above you is answering a different question about different ground.
What Grows in Highgrove
Plants matched to Highgrove's USDA zones 10a, ordered by how much hardiness margin each has here — the ones with room to spare at both ends of this town's band lead. Each links to its full growing profile.
Is it too late to plant in Highgrove?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Jan 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 13 — long-season crops need about 90 days of runway, quick greens only 30. And with a calendar this mild, the honest answer is that planting barely stops — winter opens seasons colder regions never see.
What's on the federal record near Highgrove
Closest first, within ~10 miles of Highgrove. Listing isn't leaking, and distance isn't exposure.
- SEVEN UP/RC BOTTLING COBrownfields · 0.6 mi
- OSI-RIVERSIDEBrownfields · 0.6 mi
- OSI-RIVERSIDEToxics Release Inventory · 0.6 mi
- COUNTY OF RIVERSIDE - SPRING STREET/MICHIGAN STREETBrownfields · 0.7 mi
- ROYAL INTERPACK OF NORTH AMERICA INCBrownfields · 0.7 mi
- T. M. COBB COBrownfields · 0.9 mi
- FUTURE TECH METALS INCBrownfields · 1.0 mi
- FUTURE TECH METALS INCToxics Release Inventory · 1.0 mi
- CENTER FOR ENVIRONMENTAL MICROBIOLOGYBrownfields · 1.0 mi
- BLACOH FLUID CONTROLBrownfields · 1.1 mi
- CITRUS RESEARCH BOARDBrownfields · 1.1 mi
- VALKYRIE DYNAMICSBrownfields · 1.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Highgrove'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 Highgrove.
Sources Checked
within ~10 miles of Highgrove
Severity Distribution
within ~10 miles of Highgrove
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Highgrove, Brownfields runs higher than the national average — 4,584 sites within ~10 miles of Highgrove. 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 Highgrove
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 Highgrove average
Your land is one point inside Highgrove
Everything above resolves to Highgrove as a whole — one PHZM band, read across 2K acres, with hard-freeze dates borrowed from Riverside County’s record because no 30-year normal resolves at this town’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 town 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 Highgrove Average
Highgrove Average
- ●USDA Zones 10a, averaged across Highgrove
- ●One soil character for all of Highgrove
- ●Frost dates read at Highgrove's scale: Feb 13 to Dec 13
YOUR Parcel
- ✓Your exact zone, not Highgrove's 10a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Highgrove
Pull a site-specific report for your exact address in Highgrove, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Highgrove averages can't show:
We read public map data around Highgrove — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Highgrove average
How we know this about Highgrove
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Riverside 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 town grain anywhere on this page — there is no town-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 Highgrove
When does frost risk typically end in Highgrove?
The last hard freeze (28°F) in Highgrove typically lands around Feb 13, 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 Mar 6.
When is the first frost in Highgrove?
The first hard freeze (28°F) in Highgrove typically arrives around Dec 13, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 29, so the watching starts about Nov 13 — about 303 days after the spring freeze cleared.
How long is the growing season in Highgrove?
Measured between 28°F hard freezes, Highgrove sees about 303 frost-free days — roughly Feb 13 through Dec 13, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 6 to Nov 29, about 268 days.
Is the soil safe to grow vegetables in Highgrove?
The federal record around Highgrove runs heavier than most — 5,847 documented sites, mostly Brownfields entries (4,584), the nearest Brownfields record about 0.6 miles 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 Highgrove?
From about Nov 13 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 13 (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 13. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Highgrove's scale — its 10a band and its 303-day season. Your yard writes its own version of Highgrove'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 Highgrove’s own scale
4 of the readings below were taken at Highgrove's own scale — the 2,059 acres it covers and 5,847 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Highgrove's own USDA hardiness band, zones 10aUSDA PHZM 2023
- 5,847 documented contamination sites on the federal record near Highgrove, the closest Brownfields record about 0.6 miles out from the town centreFederal environmental registers
- Highgrove's boundary and the 2,059 acres inside itUS Census TIGER/Line 2025
- Highgrove sits in the Southern California/Northern Baja Coast — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Highgrove has no normal of its own, so its county's is the closest measured readfrom Riverside County
- Soil character — no town-scale survey exists, so Highgrove's 2,059 acres read through its county's SSURGO summaryfrom Riverside County
- The candidate plant list — California's curated set, filtered to this zone band and re-ordered by how much margin each has herefrom California
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Riverside 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 Riverside County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Highgrove's 2,059 acreswhy one lot differs from the next →
- Which side of Highgrove you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,059 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.6 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 Highgrove-wide figureread your own land →
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