Oak Glen, California, sits in USDA hardiness zone 8b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Growers here do well with cabbage, fig, california poppy, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Oak Glen, 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 Oak Glen 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 Oak Glen — soil, climate, flood, and parcel records. How we handle your address.
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Oak Glen — the short answer
Oak Glen, California: USDA zone 8b, about 270 days between hard freezes, across 10K acres of town.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 9
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Dec 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~270
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 10K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 8b is Oak Glen's average, not your lot's — a low corner or a tree line moves it. Against Oak Glen's 270-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Oak Glen
Each reading below is measured for Oak Glen itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredOak Glen runs about 270 days between hard freezes — 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
MeasuredOak Glen sits in USDA hardiness zone 8b.
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 Oak Glen is in
Oak Glen sits in the Southern California Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Oak Glen's own centroid, and it is not what its county reads: San Bernardino County is mostly Mojave Basin and Range. The wider page above you is answering a different question about different ground.
What Grows in Oak Glen
Every plant below cleared Oak Glen's own zone 8b and its 270-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Oak Glen?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Feb 9; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 9 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 4 — long-season crops need about 90 days of runway, quick greens only 30. Here the calendar nearly circles: cool-season crops take the winter shift, and the next window is always close.
What's on the federal record near Oak Glen
Closest first, within ~10 miles of Oak Glen. Listing isn't leaking, and distance isn't exposure.
- 001S001W26Q002SNitrate · 0.9 mi
- 001S001W26M002SNitrate · 1.0 mi
- 001S001W26Q005SNitrate · 1.0 mi
- 001S001W36D001SNitrate · 1.0 mi
- 001S001W26L003SNitrate · 1.0 mi
- 001S001W26K001SNitrate · 1.0 mi
- 001S001W27L001SNitrate · 1.3 mi
- PILGRIM PINES CAMP AND CONFERENCE UCCRBrownfields · 1.3 mi
- THE WILDLANDS CONSERVANCYBrownfields · 1.3 mi
- 001S001W28J002SNitrate · 1.5 mi
- 001S001W28K001SNitrate · 1.7 mi
- 001S001W28P001SNitrate · 1.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Oak Glen'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 Oak Glen.
Total Sites
820
within ~10 miles of Oak Glen
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Oak Glen
Severity Distribution
within ~10 miles of Oak Glen
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Oak Glen, two things run higher than the national average within ~10 miles of Oak Glen — Brownfields (497 sites) and Nitrate (254 sites). 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.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Oak Glen
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 Oak Glen average
Your land is one point inside Oak Glen
Everything above resolves to Oak Glen as a whole — one PHZM band and one 28°F frost record, read across 10K 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 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 Oak Glen Average
Oak Glen Average
- ●USDA Zones 8b, averaged across Oak Glen
- ●One soil character for all of Oak Glen
- ●Frost dates read at Oak Glen's scale: Mar 9 to Dec 4
YOUR Parcel
- ✓Your exact zone, not Oak Glen's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Oak Glen
Pull a site-specific report for your exact address in Oak Glen, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Oak Glen averages can't show:
We read public map data around Oak Glen — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Oak Glen average
How we know this about Oak Glen
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 Oak Glen’s own record; 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 Oak Glen
When does frost risk typically end in Oak Glen?
The last hard freeze (28°F) in Oak Glen typically lands around Mar 9, 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 30.
When is the first frost in Oak Glen?
The first hard freeze (28°F) in Oak Glen typically arrives around Dec 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 20, so the watching starts about Nov 4 — about 270 days after the spring freeze cleared.
How long is the growing season in Oak Glen?
Measured between 28°F hard freezes, Oak Glen sees about 270 frost-free days — roughly Mar 9 through Dec 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 30 to Nov 20, about 235 days.
Is the soil safe to grow vegetables in Oak Glen?
The federal record around Oak Glen is a meaningful one — 820 documented sites, mostly Brownfields entries (497), the nearest Nitrate record about 0.9 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 Oak Glen?
From about Nov 4 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 4 (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 4. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Oak Glen's scale — its 8b band and its 270-day season. Your yard writes its own version of Oak Glen'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 Oak Glen’s own scale
6 of the readings below were taken at Oak Glen's own scale — its own ~270-day season between 28°F freezes, the 9,597 acres it covers and 820 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Oak Glen's own USDA hardiness band, zones 8bUSDA PHZM 2023
- Oak Glen's own 28°F hard-freeze dates, about Mar 9 and Dec 4 and the ~270-day span between themNOAA 1991–2020 Climate Normals
- 820 documented contamination sites on the federal record near Oak Glen, the closest Nitrate record about 0.9 miles out from the town centreFederal environmental registers
- Oak Glen's boundary and the 9,597 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~270-day seasonGrowable Ground crop-matching engine
- Oak Glen sits in the Southern California Mountains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Oak Glen's 9,597 acres read through its county's SSURGO summaryfrom San Bernardino County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom San Bernardino 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 Bernardino County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Oak Glen's 9,597 acreswhy one lot differs from the next →
- Which side of Oak Glen you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 9,597 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.9 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 Oak Glen-wide figureread your own land →
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