Monroe County, in Florida, sits in USDA hardiness zone 10b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Crops well matched to these conditions include artichoke, meyer lemon, california poppy, and cabbage — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Monroe County lies within the Florida Keys — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring
Monroe County holds more than one microclimate.
Soils and elevations shift across Monroe 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 Monroe County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Monroe County — the short answer
Monroe County, Florida: USDA zone 10b, no 28°F killing freeze on record — the season is year-round, across 629K acres.
- USDA zone
- 10b
- USDA PHZM 2023
- Killing freeze
- None on record
- NOAA RCC ACIS 1991–2020, county record
- County area
- 629K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. The year-round finding is measured — a 30-year record with no 28°F killing freeze in it — never inferred from missing dates.
Hardiness Zone Range
Zone 10b is Monroe County's average, not your lot's — a low corner or a tree line moves it. Against Monroe County's no killing freeze on record, see what your own ground reads.
Heat and winter chill in Monroe County
Across a year, Monroe County accumulates about 9,517 growing degree days above 50°F, about 2,132 more than the middle Florida county — ahead of 65 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 Monroe County
Across Monroe County, the ground is predominantly Histosols, where Keylargo, Cudjoe, and Islamorada are the most extensive named soil series. The soil is generally very poorly drained with a extremely gravelly sand surface. Topsoil pH runs about 8.0, moderately alkaline. Rainfall drains through hydrologic group A/D soils.
Soil order
Histosols
Drainage
Very poorly drained
Hydric soils
68%
Soil still varies lot by lot — soil types explained.
How the ground varies across Monroe County
The USDA soil survey maps 41% of Monroe County as very poorly drained — but another 41% drains differently: 20% somewhat poorly drained, 11% moderately well drained.
Keylargo is the most extensive named soil at 22% of mapped acres, then Cudjoe (16%) and Islamorada (15%).
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 Monroe County
Each reading below is measured for Monroe 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 Monroe County are very 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 Monroe County runs about pH 8.0, on the alkaline side.
Many vegetables cope, but acid-lovers like blueberries struggle, and iron and manganese lock up above about pH 7.5 — leaves yellow between the veins even in rich soil.
Elemental sulfur and generous organic matter lower pH slowly for the beds that need it; test first so you add only what the soil actually calls for.
USDA NRCS SSURGO
Season length
MeasuredMonroe County records no 28°F killing freeze at all across the 30-year station record — 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
MeasuredMonroe County sits in USDA hardiness zone 10b.
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 Monroe County is in
Monroe County sits in the Southern Florida Coastal Plain — EPA Level III, inside the wider Tropical Wet Forests. One consistent ecological setting across the whole county.
What Grows in Monroe County
We scored all 1,086 plants against Monroe County's own USDA zone 10b and its own 365-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.
Documented around Monroe County
- monarch butterfly35 documented records
Sighting records, so they follow observers as much as insects.
Safe to Grow Here?
What the federal record shows across Monroe County — and how to grow with it.
We checked the federal record across Monroe County — 587 documented sites across 6 of the 9 source types we track.
The most significant on record: 3 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 Monroe 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 Monroe County
Closest first, across Monroe County. Listing isn't leaking, and distance isn't exposure.
- RUSS'S DISCOUNT TIRE COUnderground Storage Tanks · 7.2 mi
- MO - 184Nitrate · 12.6 mi
- CIRCLE K #7330Brownfields · 16.9 mi
- KEYWADIN CLUB-KEY ISLAND MARINAUnderground Storage Tanks · 16.9 mi
- MO - 188Nitrate · 17.6 mi
- MO - 178Nitrate · 17.6 mi
- ARE LOVERSEAS BAY 20Brownfields · 23.5 mi
- OCEANIA I CONDOMINIUMUnderground Storage Tanks · 30.4 mi
- MANATEE BAY MARINE, INC.Brownfields · 44.0 mi
- POINT LAURA MARINAUnderground Storage Tanks · 44.1 mi
- GILBERTS RESORTUnderground Storage Tanks · 48.2 mi
- MANGROVE MARINE PROPERTIES LLCUnderground Storage Tanks · 48.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Monroe 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 Monroe County.
Total Sites
587
across Monroe County
Risk Level
Elevated
Highest-severity
3 Superfund sites (none NPL-listed)
Sources Checked
across Monroe County
Severity Distribution
across Monroe County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Monroe 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 Monroe County average
Your land is one point inside Monroe County
Everything above resolves to Monroe County as a whole — one PHZM band and one county frost record, read across 629K 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 Monroe County Average
Monroe County Average
- ●USDA Zones 10b, averaged across Monroe County
- ●One soil character for all of Monroe County
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Monroe County's 10b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Monroe County
Pull a site-specific report for your exact address in Monroe County, Florida — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Monroe County averages can't show:
We read public map data around Monroe County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Monroe County average
How we know this about Monroe 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 Monroe County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Monroe County
Is it too late to plant in Monroe County?
No — Monroe County has no 28°F killing freeze in the 30-year station record, so the growing season is year-round and there is no last-frost date to wait for. Planting is paced by rainfall, heat and daylength instead of by frost: start heat-lovers any month, and time cool-season crops (lettuce, brassicas, peas) for the cooler, wetter half of the year or for higher ground. Succession sowing every few weeks works all year, so the limit is what you can keep watered and harvested, not the calendar.
When does frost risk typically end in Monroe County?
It doesn't — Monroe County records no 28°F killing freeze at all across the 1991–2020 station record, so there is no spring frost date to plant after. Cold still matters with elevation: the higher you garden, the cooler the nights, and a few tropical crops sulk below about 60°F even where they never freeze.
How long is the growing season in Monroe County?
Year-round — the 1991–2020 station record for Monroe County contains no 28°F killing freeze, so there is no season to measure between freezes. What paces planting instead is heat, rainfall and daylength: the hottest, wettest stretch is the hard part for cool-season crops, not winter. Elevation is the one real exception — the higher you garden, the colder the nights get.
Is the soil safe to grow vegetables in Monroe County?
The federal record around Monroe County is a meaningful one — 587 documented sites, mostly Underground Storage Tanks entries (245), the nearest Underground Storage Tanks record about 7.2 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 Monroe County's scale — its 10b band and its no killing freeze on record. Your yard writes its own version of Monroe 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 Monroe County’s own scale
8 of the readings below were taken at Monroe County's own scale — a 30-year record with no killing freeze in it, the 3 most extensive soil series mapped here and 587 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Monroe County's own USDA hardiness band, zones 10bUSDA PHZM 2023
- No 28°F killing freeze in Monroe County's own 30-year station record — a year-round growing season, measured here rather than inheritedNOAA Regional Climate Centers ACIS, 1991-2020
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Monroe CountyUSDA NRCS SSURGO
- 587 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 7.2 miles outFederal environmental registers
- Monroe County's boundary and the 629,147 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 10b and a ~365-day seasonGrowable Ground crop-matching engine
- Monroe County sitting wholly inside the Southern Florida Coastal PlainUS EPA Level III Ecoregions
- Open occurrence records documented in Monroe County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
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 Monroe County — the ~365 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 Monroe County's 629,147 acreswhy one lot differs from the next →
- Which of those 587 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 Monroe Countyread your own land →