Cobb County, in Georgia, sits in USDA hardiness zone 8a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
A short list that earns its place here — cabbage, fig, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Cobb County lies within the Piedmont — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Cobb County holds more than one microclimate.
Soils and elevations shift across Cobb 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 Cobb County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Cobb County — the short answer
Cobb County, Georgia: USDA zone 8a, about 256 days between hard freezes, across 217K acres.
- USDA zone
- 8a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 13
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 24
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~256
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 217K 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 Cobb County's average, not your lot's — a low corner or a tree line moves it. Against Cobb County's 256-day season, see what your own ground reads.
Heat and winter chill in Cobb County
Across a year, Cobb County accumulates about 4,577 growing degree days above 50°F, about 838 fewer than the middle Georgia county — ahead of 26 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 1,601 hours below 45°F, 465 more 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 Cobb County
Across Cobb County, the ground is predominantly Ultisols, where Madison, Gwinnett, and Appling are the most extensive named soil series. The soil is generally well drained with a sandy loam surface. Topsoil pH runs about 5.5–5.8, moderately acidic. Rainfall drains through hydrologic group B soils.
Soil order
Ultisols
Drainage
Well drained
Prime farmland
15%
Hydric soils
1%
Soil still varies lot by lot — soil types explained.
How the ground varies across Cobb County
The USDA soil survey maps 77% of Cobb County as well drained — but another 15% drains differently: 6% moderately well drained, 6% somewhat poorly drained.
Madison is the most extensive named soil at 28% of mapped acres, then Gwinnett (19%) and Appling (11%).
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 Cobb County
Each reading below is measured for Cobb 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 Cobb 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 Cobb County runs about pH 5.5–5.8, 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
MeasuredCobb County runs about 256 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
MeasuredCobb 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 Cobb County is in
Cobb 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 Cobb County
We scored all 1,086 plants against Cobb County's own USDA zone 8a and its own 256-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 Cobb County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 13; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 24 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
Documented around Cobb County
- Japanese beetle8 documented records
- monarch butterfly13 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Cobb County
USGS estimates 370 lb of 2,4-d on Cobb County farmland in 2019, its largest by weight, ahead of Propiconazole (120 lb) and Azoxystrobin (104 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 Cobb County — and how to grow with it.
We checked the federal record across Cobb County — 1,709 documented sites across 6 of the 9 source types we track.
The most significant on record: 20 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 Cobb 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 Cobb County
Closest first, across Cobb County. Listing isn't leaking, and distance isn't exposure.
- REDWOOD DR PUMPING STATIONUnderground Storage Tanks · 0.6 mi
- CLARK ICE COUnderground Storage Tanks · 0.8 mi
- RITE AID #11713Brownfields · 0.8 mi
- WOOD & FULERTON INCUnderground Storage Tanks · 0.8 mi
- BP #24073Underground Storage Tanks · 0.8 mi
- BST/POWDER SPRINGS/F5302Underground Storage Tanks · 0.8 mi
- CHEVRON FOOD MARTUnderground Storage Tanks · 0.8 mi
- MARATHONUnderground Storage Tanks · 0.9 mi
- QUICK THRIFT #931Underground Storage Tanks · 0.9 mi
- QUALITY CLEANERSBrownfields · 0.9 mi
- KROGER #455Brownfields · 0.9 mi
- KROGER GA-455Underground Storage Tanks · 0.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Cobb 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 Cobb County.
Total Sites
1,709
across Cobb County
Risk Level
Elevated
Highest-severity
20 Superfund sites (none NPL-listed)
Sources Checked
across Cobb County
Severity Distribution
across Cobb County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Cobb County, Underground Storage Tanks runs higher than the national average — 1,160 sites across Cobb County. 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 Cobb 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 Cobb County average
Your land is one point inside Cobb County
Everything above resolves to Cobb County as a whole — one PHZM band and one county frost record, read across 217K 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 Cobb County Average
Cobb County Average
- ●USDA Zones 8a, averaged across Cobb County
- ●One soil character for all of Cobb County
- ●Frost dates read at Cobb County's scale: Mar 13 to Nov 24
YOUR Parcel
- ✓Your exact zone, not Cobb County's 8a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Cobb County
Pull a site-specific report for your exact address in Cobb County, Georgia — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Cobb County averages can't show:
We read public map data around Cobb County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Cobb County average
How we know this about Cobb 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 Cobb County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Cobb County
When does frost risk typically end in Cobb County?
The last hard freeze (28°F) in Cobb County typically lands around Mar 13, 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 3.
How long is the growing season in Cobb County?
Measured between 28°F hard freezes, Cobb County sees about 256 frost-free days — roughly Mar 13 through Nov 24, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 3 to Nov 10, about 221 days.
Is the soil safe to grow vegetables in Cobb County?
The federal record around Cobb County is a meaningful one — 1,709 documented sites, mostly Underground Storage Tanks entries (1,160), the nearest Underground Storage Tanks record about 0.6 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 Cobb County's scale — its 8a band and its 256-day season. Your yard writes its own version of Cobb 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 Cobb County’s own scale
9 of the readings below were taken at Cobb County's own scale — its own ~256-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,709 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Cobb County's own USDA hardiness band, zones 8aUSDA PHZM 2023
- Cobb County's own 28°F hard-freeze dates and its ~256-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Cobb CountyUSDA NRCS SSURGO
- 1,709 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
- Cobb County's boundary and the 217,408 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8a and a ~256-day seasonGrowable Ground crop-matching engine
- Cobb County sitting wholly inside the PiedmontUS EPA Level III Ecoregions
- Open occurrence records documented in Cobb County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Cobb 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 Cobb County — the ~256 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 Cobb County's 217,408 acreswhy one lot differs from the next →
- Which of those 1,709 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 Cobb Countyread your own land →