Union County, in South Carolina, sits in USDA hardiness zone 8a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
On paper, cabbage, fig, california poppy, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Union County lies within the Upstate South Carolina and the Piedmont — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
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 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Union County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Union County — the short answer
Union County, South Carolina: USDA zone 8a, about 237 days between hard freezes, across 329K acres.
- USDA zone
- 8a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 20
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 12
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~237
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 329K 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 8a is Union County's average, not your lot's — a low corner or a tree line moves it. Against Union County's 237-day season, see what your own ground reads.
Heat and winter chill in Union County
Across a year, Union County accumulates about 4,645 growing degree days above 50°F, about 503 fewer than the middle South Carolina county — ahead of 6 of South Carolina’s 46 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 1,636 hours below 45°F, 274 more than the South Carolina middle of 1,362. 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 Union County
Across Union County, the ground is predominantly Ultisols, where Madison, Wilkes, and Cecil are the most extensive named soil series. The soil is generally well drained with a sandy loam surface. Topsoil pH runs about 5.3–6.0, moderately acidic. Rainfall drains through hydrologic group B soils.
Soil order
Ultisols
Drainage
Well drained
Prime farmland
9%
Hydric soils
2%
Soil still varies lot by lot — soil types explained.
How the ground varies across Union County
The USDA soil survey maps 82% of Union County as well drained — but another 17% drains differently: 7% moderately well drained, 7% somewhat poorly drained.
Madison is the most extensive named soil at 29% of mapped acres, then Wilkes (19%) and Cecil (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 Union County
Each reading below is measured for Union 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 Union County are well drained, in hydrologic group B — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Union County runs about pH 5.3–6.0, 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
MeasuredUnion County runs about 237 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredUnion County sits in USDA hardiness zone 8a.
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 Union County is in
Union County sits in the Piedmont — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in Union County
We scored all 1,086 plants against Union County's own USDA zone 8a and its own 237-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 South Carolina profile.
Is it too late to plant in Union County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Feb 20; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 20 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 12 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Documented around Union County
Survey cells within 31 miles of Union County checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 71 miles off. What to watch for.
What gets applied to farmland in Union County
USGS estimates 4,791 lb of 2,4-d on Union County farmland in 2019, its largest by weight, ahead of Glyphosate (1,094 lb) and Atrazine (604 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 Union County — and how to grow with it.
We checked the federal record across Union County — 171 documented sites across 6 of the 9 source types we track.
The most significant on record: 17 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.
What's on the federal record near Union County
Closest first, across Union County. Listing isn't leaking, and distance isn't exposure.
- RALPH KIRBY CHEVROLET BUICK PONTIAC OLDSMOBILE INCUnderground Storage Tanks · 0.6 mi
- CRICKET 3846Underground Storage Tanks · 0.6 mi
- KIRBY CHEVROLET BUICK PONTIAC OLDSBrownfields · 0.6 mi
- MEANSVILLE RILEY W/D (SC4420001)PFAS · 0.8 mi
- UNION CITY OF (4410001)PFAS · 0.8 mi
- ENERGY MARKET 4508Underground Storage Tanks · 0.8 mi
- COXUnderground Storage Tanks · 1.0 mi
- DD'S FOOD MARTUnderground Storage Tanks · 1.1 mi
- DIXIE CURB MARKETUnderground Storage Tanks · 1.2 mi
- UNION WORK CENTERUnderground Storage Tanks · 1.2 mi
- SUNSHINE ONE HOUR CLEANERBrownfields · 1.2 mi
- UNION COUNTY AIRPORTUnderground Storage Tanks · 1.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Union 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 Union County.
Total Sites
171
across Union County
Risk Level
Moderate
Highest-severity
17 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, two things run higher than the national average across Union County — Toxics Release Inventory (17 sites) and Underground Storage Tanks (110 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
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 1,086 plant recommendations.
25+ data sources read at your address, not the Union County average
Your land is one point inside Union County
Everything above resolves to Union County as a whole — one PHZM band and one county frost record, read across 329K 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 Union County Average
Union County Average
- ●USDA Zones 8a, averaged across Union County
- ●One soil character for all of Union County
- ●Frost dates read at Union County's scale: Mar 20 to Nov 12
YOUR Parcel
- ✓Your exact zone, not Union County's 8a
- ✓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, South Carolina — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Union County averages can't show:
We read public map data around Union County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Union County average
How we know this about Union 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 Union County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Union County
When does frost risk typically end in Union County?
The last hard freeze (28°F) in Union County typically lands around Mar 20, 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 Apr 10.
How long is the growing season in Union County?
Measured between 28°F hard freezes, Union County sees about 237 frost-free days — roughly Mar 20 through Nov 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 10 to Oct 29, about 202 days.
Is the soil safe to grow vegetables in Union County?
The federal record around Union County shows 171 documented sites, mostly Underground Storage Tanks entries (110), the nearest Underground Storage Tanks record about 0.6 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.
Everything above is measured at Union County's scale — its 8a band and its 237-day season. Your yard writes its own version of Union 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 South Carolina's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Union County’s own scale
8 of the readings below were taken at Union County's own scale — its own ~237-day span between 28°F freezes, the 3 most extensive soil series mapped here and 171 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Union County's own USDA hardiness band, zones 8aUSDA PHZM 2023
- Union County's own 28°F hard-freeze dates and its ~237-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Union CountyUSDA NRCS SSURGO
- 171 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.6 miles outFederal environmental registers
- Union County's boundary and the 328,706 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8a and a ~237-day seasonGrowable Ground crop-matching engine
- Union County sitting wholly inside the PiedmontUS EPA Level III Ecoregions
- Which agricultural compounds go onto Union County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every South Carolina grower plans around — written at state scale, so they stay on the state guidefrom South Carolina
What this page can’t tell you
- How the season shifts across Union County — the ~237 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 Union County's 328,706 acreswhy one lot differs from the next →
- Which of those 171 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 Union Countyread your own land →