St. Johns County, in Florida, sits in USDA hardiness zone 9b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
These conditions suit okra, meyer lemon, california poppy, and artichoke — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
St. Johns County lies within the Northeast Florida — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
St. Johns County holds more than one microclimate.
Soils and elevations shift across St. Johns County, so your frost dates and drainage aren't the county average. 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 St. Johns County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
St. Johns County — the short answer
St. Johns County, Florida: USDA zone 9b, about 329 days between hard freezes, across 384K acres.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 25
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 20
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~329
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 384K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 9b is St. Johns County's average, not your lot's — a low corner or a tree line moves it. Against St. Johns County's 329-day season, see what your own ground reads.
Heat and winter chill in St. Johns County
Across a year, St. Johns County accumulates about 7,385 growing degree days above 50°F, right at the Florida middle — ahead of 33 of Florida’s 67 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Winter banks about 0 hours below 45°F, 36 fewer than the Florida middle of 36. Chill is what tells a fruit tree its dormancy is over, and it is set by climate rather than by anything you can build.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in St. Johns County
Across St. Johns County, the ground is predominantly Spodosols, where Riviera, Myakka, and Pomona are the most extensive named soil series. The soil is generally poorly drained with a fine sand surface. Topsoil pH runs about 5.0–5.6, strongly acidic. Rainfall drains through hydrologic group A/D soils.
Soil order
Spodosols
Drainage
Poorly drained
Hydric soils
48%
Soil still varies lot by lot — soil types explained.
How the ground varies across St. Johns County
The USDA soil survey maps 55% of St. Johns County as poorly drained — but another 37% drains differently: 24% very poorly drained, 7% somewhat poorly drained.
Riviera is the most extensive named soil at 12% of mapped acres, then Myakka (11%) and Pomona (9%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in St. Johns County
Each reading below is measured for St. Johns County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across St. Johns County are poorly drained, in hydrologic group A/D — ground that sheds water slowly.
Beds can stay saturated for days after heavy rain, and the roots of most vegetables, berries, and fruit trees suffocate or rot in soil that never drains.
Raised beds or mounded rows lift roots above the wet zone; choose water-tolerant crops for the lowest spots.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across St. Johns County runs about pH 5.0–5.6, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Season length
MeasuredSt. Johns County runs about 329 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
MeasuredSt. Johns County 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 St. Johns County is in
St. Johns County sits in the Southern Coastal Plain — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in St. Johns County
We scored all 1,086 plants against St. Johns County's own USDA zone 9b and its own 329-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Florida profile.
Is it too late to plant in St. Johns County?
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 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jan 25 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 20 — 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.
Documented around St. Johns County
- monarch butterfly17 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in St. Johns County
USGS estimates 8,226 lb of Metolachlor-s on St. Johns County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (8,226 lb) and Glyphosate (4,042 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across St. Johns County — and how to grow with it.
We checked the federal record across St. Johns County — 580 documented sites across 6 of the 9 source types we track.
The most significant on record: 4 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across St. Johns County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near St. Johns County
Closest first, across St. Johns County. Listing isn't leaking, and distance isn't exposure.
- ST AUGUSTINE AIRCRAFT SERVICE INCBrownfields · 1.3 mi
- KANGAROO EXPRESS INC #1060Brownfields · 1.4 mi
- KANGAROO EXPRESS INC #1255Brownfields · 1.4 mi
- RIVERSIDE DRYCLEANERS OF ST AUGUSTINE INBrownfields · 1.4 mi
- ST JOHNS CNTY-MAINLAND WATER SYSTEMUnderground Storage Tanks · 1.7 mi
- SPECTRUM COLORBrownfields · 1.8 mi
- UNITED PARCEL SERVICE INCBrownfields · 2.0 mi
- UNITED PARCEL SRVCUnderground Storage Tanks · 2.0 mi
- ANASTASIA MOSQUITO CONTROL DISTRICTBrownfields · 2.0 mi
- MURRAY MIDDLE SCHOOLBrownfields · 2.0 mi
- ST JOHNS COUNTY HOLMES BLVD SITEUnderground Storage Tanks · 2.1 mi
- ROACH RESIDENCEBrownfields · 2.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from St. Johns County'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 St. Johns County.
Total Sites
580
across St. Johns County
Risk Level
Elevated
Highest-severity
4 Superfund sites (none NPL-listed)
Sources Checked
across St. Johns County
Severity Distribution
across St. Johns County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around St. Johns County, PFAS runs higher than the national average — 8 sites across St. Johns County. That's not a problem with your land — it's information about it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in St. Johns County
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 St. Johns County average
Your land is one point inside St. Johns County
Everything above resolves to St. Johns County as a whole — one PHZM band and one county frost record, read across 384K 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 county 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 county average.
Your Lot vs the St. Johns County Average
St. Johns County Average
- ●USDA Zones 9b, averaged across St. Johns County
- ●One soil character for all of St. Johns County
- ●Frost dates read at St. Johns County's scale: Jan 25 to Dec 20
YOUR Parcel
- ✓Your exact zone, not St. Johns County's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in St. Johns County
Pull a site-specific report for your exact address in St. Johns County, Florida — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that St. Johns County averages can't show:
We read public map data around St. Johns County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the St. Johns County average
How we know this about St. Johns County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where St. Johns County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about St. Johns County
When does frost risk typically end in St. Johns County?
The last hard freeze (28°F) in St. Johns County typically lands around Jan 25, 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 15.
How long is the growing season in St. Johns County?
Measured between 28°F hard freezes, St. Johns County sees about 329 frost-free days — roughly Jan 25 through Dec 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 15 to Dec 6, about 294 days.
Is the soil safe to grow vegetables in St. Johns County?
The federal record around St. Johns County is a meaningful one — 580 documented sites, mostly Underground Storage Tanks entries (323), the nearest Brownfields record about 1.3 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.
Everything above is measured at St. Johns County's scale — its 9b band and its 329-day season. Your yard writes its own version of St. Johns County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Florida's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at St. Johns County’s own scale
9 of the readings below were taken at St. Johns County's own scale — its own ~329-day span between 28°F freezes, the 3 most extensive soil series mapped here and 580 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- St. Johns County's own USDA hardiness band, zones 9bUSDA PHZM 2023
- St. Johns County's own 28°F hard-freeze dates and its ~329-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in St. Johns CountyUSDA NRCS SSURGO
- 580 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Brownfields record about 1.3 miles outFederal environmental registers
- St. Johns County's boundary and the 384,424 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~329-day seasonGrowable Ground crop-matching engine
- St. Johns County sitting wholly inside the Southern Coastal PlainUS EPA Level III Ecoregions
- Open occurrence records documented in St. Johns County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto St. Johns County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Florida grower plans around — written at state scale, so they stay on the state guidefrom Florida
What this page can’t tell you
- How the season shifts across St. Johns County — the ~329 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among St. Johns County's 384,424 acreswhy one lot differs from the next →
- Which of those 580 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over St. Johns Countyread your own land →