Irwin County, in Georgia, sits in USDA hardiness zone 9a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
The conditions favor artichoke, fig, california poppy, and cabbage, among others — though every individual site edits that list with its own soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Irwin County holds more than one microclimate.
Soils and elevations shift across Irwin 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 Irwin County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Irwin County — the short answer
Irwin County, Georgia: USDA zone 9a, about 298 days between hard freezes, across 227K acres.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 11
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 6
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~298
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 227K 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 9a is Irwin County's average, not your lot's — a low corner or a tree line moves it. Against Irwin County's 298-day season, see what your own ground reads.
Heat and winter chill in Irwin County
Across a year, Irwin County accumulates about 6,042 growing degree days above 50°F, about 627 more than the middle Georgia county — ahead of 123 of Georgia’s 159 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 665 hours below 45°F, 471 fewer than the Georgia middle of 1,136. 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 Irwin County
Across Irwin County, the ground is predominantly Ultisols, where Tifton, Alapaha, and Plummer are the most extensive named soil series. The soil is generally well drained with a loamy sand surface. Topsoil pH runs about 4.8–6.0, strongly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Ultisols
Drainage
Well drained
Prime farmland
36%
Hydric soils
33%
Soil still varies lot by lot — soil types explained.
How the ground varies across Irwin County
The USDA soil survey maps 46% of Irwin County as well drained — but another 51% drains differently: 29% poorly drained, 10% somewhat poorly drained.
Tifton is the most extensive named soil at 32% of mapped acres, then Alapaha (14%) and Plummer (8%).
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 Irwin County
Each reading below is measured for Irwin 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 Irwin 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 Irwin County runs about pH 4.8–6.0, 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
Wet ground
MeasuredAbout 33% of Irwin County is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredIrwin County runs about 298 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
The kind of country Irwin County is in
Irwin County sits in the Southeastern Plains — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in Irwin County
We scored all 1,086 plants against Irwin County's own USDA zone 9a and its own 298-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 Georgia profile.
Is it too late to plant in Irwin County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Jan 14; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 11 (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. And with a calendar this mild, the honest answer is that planting barely stops — winter opens seasons colder regions never see.
What gets applied to farmland in Irwin County
USGS estimates 71,809 lb of Glyphosate on Irwin County farmland in 2019, its largest by weight, ahead of Acetochlor (36,740 lb) and Metolachlor & Metolachlor-s (26,335 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 Irwin County — and how to grow with it.
We checked the federal record across Irwin County — 51 documented sites across 4 of the 9 source types we track.
The most significant on record: 1 Toxics Release Inventory facility. Active industrial facilities reporting chemical releases to air, water, and land.
The federal record across Irwin 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 Irwin County
Closest first, across Irwin County. Listing isn't leaking, and distance isn't exposure.
- IRWIN COUNTY EMCUnderground Storage Tanks · 1.2 mi
- T&W AUTO REPAIRUnderground Storage Tanks · 1.2 mi
- IRWIN COUNTY HOSPITALUnderground Storage Tanks · 1.6 mi
- FLASH FOODS #169Underground Storage Tanks · 1.6 mi
- OMNI FOOD STOREUnderground Storage Tanks · 1.6 mi
- CROWN/FAST FATE GA-541\ZIPPY MARUnderground Storage Tanks · 1.6 mi
- CITY OF OCILLAUnderground Storage Tanks · 1.7 mi
- GA FCUnderground Storage Tanks · 1.7 mi
- LAX EXCHANGEUnderground Storage Tanks · 1.7 mi
- TANKERSLEY OIL CO INCUnderground Storage Tanks · 1.7 mi
- G&G FOOD MARTUnderground Storage Tanks · 1.7 mi
- BARFIELD SERVICE STATIONUnderground Storage Tanks · 1.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Irwin 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 Irwin County.
Total Sites
51
across Irwin County
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
across Irwin County
Severity Distribution
across Irwin County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Irwin County, two things run higher than the national average across Irwin County — Nitrate (16 sites) and Underground Storage Tanks (32 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Irwin 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 Irwin County average
Your land is one point inside Irwin County
Everything above resolves to Irwin County as a whole — one PHZM band and one county frost record, read across 227K 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 Irwin County Average
Irwin County Average
- ●USDA Zones 9a, averaged across Irwin County
- ●One soil character for all of Irwin County
- ●Frost dates read at Irwin County's scale: Feb 11 to Dec 6
YOUR Parcel
- ✓Your exact zone, not Irwin County's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Irwin County
Pull a site-specific report for your exact address in Irwin County, Georgia — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Irwin County averages can't show:
We read public map data around Irwin County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Irwin County average
How we know this about Irwin 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 Irwin County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Irwin County
When does frost risk typically end in Irwin County?
The last hard freeze (28°F) in Irwin County typically lands around Feb 11, 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 4.
How long is the growing season in Irwin County?
Measured between 28°F hard freezes, Irwin County sees about 298 frost-free days — roughly Feb 11 through Dec 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 4 to Nov 22, about 263 days.
Is the soil safe to grow vegetables in Irwin County?
The federal record around Irwin County shows 51 documented sites, mostly Underground Storage Tanks entries (32), the nearest Underground Storage Tanks record about 1.2 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 Irwin County's scale — its 9a band and its 298-day season. Your yard writes its own version of Irwin 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 Georgia's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Irwin County’s own scale
8 of the readings below were taken at Irwin County's own scale — its own ~298-day span between 28°F freezes, the 3 most extensive soil series mapped here and 51 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Irwin County's own USDA hardiness band, zones 9aUSDA PHZM 2023
- Irwin County's own 28°F hard-freeze dates and its ~298-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Irwin CountyUSDA NRCS SSURGO
- 51 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 1.2 miles outFederal environmental registers
- Irwin County's boundary and the 226,792 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~298-day seasonGrowable Ground crop-matching engine
- Irwin County sitting wholly inside the Southeastern PlainsUS EPA Level III Ecoregions
- Which agricultural compounds go onto Irwin County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Georgia grower plans around — written at state scale, so they stay on the state guidefrom Georgia
What this page can’t tell you
- How the season shifts across Irwin County — the ~298 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 Irwin County's 226,792 acreswhy one lot differs from the next →
- Which of those 51 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 Irwin Countyread your own land →