Granite Hills, California, sits in USDA hardiness zone 10a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
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 Granite Hills, 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 Granite Hills 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 Granite Hills — soil, climate, flood, and parcel records. How we handle your address.
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Granite Hills — the short answer
Granite Hills, California: USDA zone 10a, about 311 days between hard freezes, across 2K acres of town.
- USDA zone
- 10a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 3
- San Diego County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 11
- San Diego County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~311
- San Diego 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 San Diego County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 10a is Granite Hills's average, not your lot's — a low corner or a tree line moves it. Against Granite Hills's 311-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Granite Hills
Each reading below is measured for Granite Hills itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsGranite Hills runs about 311 days between hard freezes (read from San Diego County, the closest normal to Granite Hills) — 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
MeasuredGranite Hills 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 Granite Hills is in
Granite Hills sits in the Southern California/Northern Baja Coast — EPA Level III, inside the wider Mediterranean California. That is read at Granite Hills's own centroid rather than borrowed from San Diego County.
What Grows in Granite Hills
Every plant below cleared Granite Hills's own zone 10a and its 311-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Granite Hills?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Jan 6; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 3 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 11 — 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 Granite Hills
Spotted lanternfly documented 29 miles from Granite Hills, first recorded 2022. What to watch for.
What's on the federal record near Granite Hills
Closest first, within ~10 miles of Granite Hills. Listing isn't leaking, and distance isn't exposure.
- PACIFIC WEST BUILDERS INC.Brownfields · 2100 ft
- WILLIAM PAYNEBrownfields · 2200 ft
- GROSSMONT UHSD - GRANITE HILLS HSBrownfields · 0.6 mi
- HEARTLAND CONCRETE PUMPINGBrownfields · 0.7 mi
- GREENFIELD MOBILUnderground Storage Tanks · 0.8 mi
- MOBILBrownfields · 0.8 mi
- ALBERTSONS 3202Brownfields · 0.9 mi
- RILEY AUTOMOTIVEBrownfields · 0.9 mi
- ALBERTSON'S # 3202Brownfields · 0.9 mi
- G&M OIL CO #59Brownfields · 1.0 mi
- Chevron (G&M #59)Underground Storage Tanks · 1.0 mi
- E & M AUTO PARTSBrownfields · 1.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Granite Hills'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 Granite Hills.
Total Sites
2,909
within ~10 miles of Granite Hills
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Granite Hills
Severity Distribution
within ~10 miles of Granite Hills
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Granite Hills, Brownfields runs higher than the national average — 2,654 sites within ~10 miles of Granite Hills. 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 Granite Hills
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 Granite Hills average
Your land is one point inside Granite Hills
Everything above resolves to Granite Hills as a whole — one PHZM band, read across 2K acres, with hard-freeze dates borrowed from San Diego 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 Granite Hills Average
Granite Hills Average
- ●USDA Zones 10a, averaged across Granite Hills
- ●One soil character for all of Granite Hills
- ●Frost dates read at Granite Hills's scale: Feb 3 to Dec 11
YOUR Parcel
- ✓Your exact zone, not Granite Hills's 10a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Granite Hills
Pull a site-specific report for your exact address in Granite Hills, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Granite Hills averages can't show:
We read public map data around Granite Hills — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Granite Hills average
How we know this about Granite Hills
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 San Diego 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 Granite Hills
When does frost risk typically end in Granite Hills?
The last hard freeze (28°F) in Granite Hills typically lands around Feb 3, 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 24.
When is the first frost in Granite Hills?
The first hard freeze (28°F) in Granite Hills typically arrives around Dec 11, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 27, so the watching starts about Nov 11 — about 311 days after the spring freeze cleared.
How long is the growing season in Granite Hills?
Measured between 28°F hard freezes, Granite Hills sees about 311 frost-free days — roughly Feb 3 through Dec 11, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 24 to Nov 27, about 276 days.
Is the soil safe to grow vegetables in Granite Hills?
The federal record around Granite Hills is a meaningful one — 2,909 documented sites, mostly Brownfields entries (2,654), the nearest Brownfields record about 0.4 miles 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.
How do I protect my plants from frost in Granite Hills?
From about Nov 11 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 11 (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 11. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Granite Hills's scale — its 10a band and its 311-day season. Your yard writes its own version of Granite Hills'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 Granite Hills’s own scale
6 of the readings below were taken at Granite Hills's own scale — the 1,788 acres it covers and 2,909 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Granite Hills's own USDA hardiness band, zones 10aUSDA PHZM 2023
- 2,909 documented contamination sites on the federal record near Granite Hills, the closest Brownfields record about 0.4 miles out from the town centreFederal environmental registers
- Granite Hills's boundary and the 1,788 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 10a and a ~311-day seasonGrowable Ground crop-matching engine
- The ecoregion at Granite Hills's own centroid, the Southern California/Northern Baja CoastUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Granite Hillslydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Granite Hills has no normal of its own, so its county's is the closest measured readfrom San Diego County
- Soil character — no town-scale survey exists, so Granite Hills's 1,788 acres read through its county's SSURGO summaryfrom San Diego County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom San Diego 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 Diego County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Granite Hills's 1,788 acreswhy one lot differs from the next →
- Which side of Granite Hills you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,788 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.4 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 Granite Hills-wide figureread your own land →
More in California
Wider growing context
What grows across CaliforniaGranite Hills sits outside our named growing regions, so California as a whole is its closest context here.
Nearby growing guides