Union County, in Florida, sits in USDA hardiness zone 9a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
On paper, mango, tomato, orange, and sweet potato all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring
Union County holds more than one microclimate.
Soils and elevations shift across Union County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Quick Facts
USDA Zones
9a
Last Frost (state avg.)
Jan 1 - Mar 15
First Frost (state avg.)
Nov 15 - never (south FL)
County Area
156K acres
Hardiness Zone Range
Growing Season
Zone maps are averages across Union County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Union County
Across Union County, the ground is predominantly Ultisols, where Pelham, Sapelo, and Plummer are the most extensive named soil series. The soil is generally poorly drained with a fine sand surface. Topsoil pH runs about 4.6, very strongly acidic. Rainfall drains through hydrologic group B/D soils.
Soil order
Ultisols
Drainage
Poorly drained
Hydric soils
40%
Soil still varies lot by lot — soil types explained.
What Grows in Union County
Plants matched to Union County's USDA zones 9a — each links to its full growing profile.
Growing Challenges in Florida
What an experienced grower plans around here — each one has a move.
Sandy soils drain too fast and hold few nutrients — frequent fertilization needed
Build organic matter relentlessly — compost and cover crops turn sand into soil that holds both water and food.
Humidity drives fungal diseases (powdery mildew, black spot, rust)
Space plants for airflow, water at the base in the morning, and choose resistant varieties — your extension office lists the proven ones.
Hurricane season (June-November) can destroy plantings
Favor wind-tough perennials, stake young trees properly, and keep fall crops in containers you can move ahead of a storm.
Nematodes are a serious pest in sandy FL soils
Summer solarization and crop-family rotation knock nematodes back — your extension office can confirm the species from a soil sample.
For cultivar selection, pest pressure, and planting-time guidance specific to Florida, the UF/IFAS Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Union County — and how to grow with it.
We checked the federal record across Union County — 74 documented sites across 5 of the 9 source types we track.
The most significant on record: 2 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
The federal record across Union County is a modest one — a typical footprint for a growing area. Nothing here calls for alarm; it's worth knowing which recorded sites sit closest to where you grow, and each one on the map carries its type and location. If one turns out to be a near neighbor, a one-time soil test settles the question.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Total Sites
74
across Union County
Risk Level
Moderate
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
across Union County
Severity Distribution
across Union County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Union County, Underground Storage Tanks runs higher than the national average — 46 sites nearby. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
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 Union County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Union County Average
- ●USDA Zones 9a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Union County
Pull a site-specific report for your exact address in Union County, Florida — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Union County, Florida
- USDA Hardiness Zones: 9a (USDA PHZM 2023)
- Last Spring Frost (state avg.): Jan 1 - Mar 15 (NOAA 30-Year Climate Normals)
- First Fall Frost (state avg.): Nov 15 - never (south FL) (NOAA 30-Year Climate Normals)
- County Land Area: 156K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Union County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Union County, Florida?
Union County sits in USDA hardiness zone 9a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
When does frost risk typically end in Union County?
Union County follows Florida's statewide frost window: last spring frost around Jan 1 - Mar 15 and first fall frost around Nov 15 - never (south FL), per NOAA 30-year climate normals (1991–2020). Frost dates shift with elevation and local microclimate, so watch your own site's cold pockets.
What vegetables grow in Union County?
Union County's zone 9a supports a wide range — strong performers include Mango, Tomato, Orange, Sweet Potato, and Banana. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Union County, really?
Officially, Union County sits in USDA zone 9a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Union County?
The federal record around Union County shows 74 documented sites — 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.
Just moved to Union County — what should I know before planting?
Start with three facts. Union County sits in USDA zone 9a, which sets what survives winter; the statewide frost window runs about Jan 1 - Mar 15 to Nov 15 - never (south FL) (NOAA 30-year climate normals); and 74 documented sites sit on the federal record — a typical footprint for a growing area, worth a look on the contamination map before food beds. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Union County average. Your yard writes its own version — 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.