Keystone Heights, Florida, sits in USDA hardiness zone 9a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
A short list that earns its place here — artichoke, fig, california poppy, and cabbage — with any one site's soil, sun, and drainage making the final cut.
Even in Keystone Heights, 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 Keystone Heights 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 Keystone Heights — soil, climate, flood, and parcel records. How we handle your address.
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Keystone Heights — the short answer
Keystone Heights, Florida: USDA zone 9a, about 300 days between hard freezes, across 688 acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 9
- Clay County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 6
- Clay County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~300
- Clay County normal — NOAA 1991–2020, nearest to this town
- City area
- 688 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 Clay County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Keystone Heights's average, not your lot's — a low corner or a tree line moves it. Against Keystone Heights's 300-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Keystone Heights
Each reading below is measured for Keystone Heights itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsKeystone Heights runs about 300 days between hard freezes (read from Clay County, the closest normal to Keystone Heights) — 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
MeasuredKeystone Heights sits in USDA hardiness zone 9a.
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 Keystone Heights is in
Keystone Heights sits in the Southern Coastal Plain — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Keystone Heights's own centroid rather than borrowed from Clay County.
What Grows in Keystone Heights
Every plant below cleared Keystone Heights's own zone 9a and its 300-day season. Each card opens that plant's Florida profile. How we score.
Is it too late to plant in Keystone Heights?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Jan 12; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 9 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 6 — 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.
What's on the federal record near Keystone Heights
Closest first, within ~10 miles of Keystone Heights. Listing isn't leaking, and distance isn't exposure.
- KEYSTONE HEIGHTS CITY-BARNUnderground Storage Tanks · 750 ft
- SPEEDWAY #6869Underground Storage Tanks · 1200 ft
- BELLSOUTH TEL INC #33454 KYHGFLMAUnderground Storage Tanks · 1200 ft
- BP-CATLETTSUnderground Storage Tanks · 1300 ft
- REED'S AUTO PARTSUnderground Storage Tanks · 1500 ft
- CIRCLE K #2721323Underground Storage Tanks · 1600 ft
- CLAY CNTY SCHOOL BD-MIDDLEBURG FACUnderground Storage Tanks · 1600 ft
- ORANGE PARK READY MIXUnderground Storage Tanks · 1600 ft
- CIRCLE K #2722112Underground Storage Tanks · 1600 ft
- KEYSTONE KWIK LUBEBrownfields · 1700 ft
- CLAY ELECTRIC COOP INCBrownfields · 1700 ft
- CVS PHARMACY #4627Brownfields · 2000 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Keystone Heights'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 Keystone Heights.
Total Sites
123
within ~10 miles of Keystone Heights
Risk Level
Moderate
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Keystone Heights
Severity Distribution
within ~10 miles of Keystone Heights
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Keystone Heights, Underground Storage Tanks runs higher than the national average — 76 sites within ~10 miles of Keystone Heights. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Keystone Heights
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 Keystone Heights average
Your land is one point inside Keystone Heights
Everything above resolves to Keystone Heights as a whole — one PHZM band, read across 688 acres, with hard-freeze dates borrowed from Clay 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 Keystone Heights Average
Keystone Heights Average
- ●USDA Zones 9a, averaged across Keystone Heights
- ●One soil character for all of Keystone Heights
- ●Frost dates read at Keystone Heights's scale: Feb 9 to Dec 6
YOUR Parcel
- ✓Your exact zone, not Keystone Heights's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Keystone Heights
Pull a site-specific report for your exact address in Keystone Heights, Florida — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Keystone Heights averages can't show:
We read public map data around Keystone Heights — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Keystone Heights average
How we know this about Keystone Heights
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 Clay 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 Keystone Heights
When does frost risk typically end in Keystone Heights?
The last hard freeze (28°F) in Keystone Heights typically lands around Feb 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 2.
When is the first frost in Keystone Heights?
The first hard freeze (28°F) in Keystone Heights typically arrives around Dec 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 22, so the watching starts about Nov 6 — about 300 days after the spring freeze cleared.
How long is the growing season in Keystone Heights?
Measured between 28°F hard freezes, Keystone Heights sees about 300 frost-free days — roughly Feb 9 through Dec 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 2 to Nov 22, about 265 days.
Is the soil safe to grow vegetables in Keystone Heights?
The federal record around Keystone Heights shows 123 documented sites, mostly Underground Storage Tanks entries (76), the nearest Underground Storage Tanks record about 0.1 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Keystone Heights?
From about Nov 6 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 6 (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 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Keystone Heights's scale — its 9a band and its 300-day season. Your yard writes its own version of Keystone Heights'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 Keystone Heights’s own scale
5 of the readings below were taken at Keystone Heights's own scale — the 688 acres it covers and 123 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Keystone Heights's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 123 documented contamination sites on the federal record near Keystone Heights, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Keystone Heights's boundary and the 688 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~300-day seasonGrowable Ground crop-matching engine
- The ecoregion at Keystone Heights's own centroid, the Southern Coastal PlainUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Keystone Heights has no normal of its own, so its county's is the closest measured readfrom Clay County
- Soil character — no town-scale survey exists, so Keystone Heights's 688 acres read through its county's SSURGO summaryfrom Clay County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Clay County
- The growing challenges every Florida grower plans around — written at state scale, so they stay on the state guidefrom Florida
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Clay County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Keystone Heights's 688 acreswhy one lot differs from the next →
- Which side of Keystone Heights you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 688 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 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 Keystone Heights-wide figureread your own land →
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