Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 31042 — Irwinton, GA

ZIP code 31042 (Irwinton, Wilkinson County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 12 and the first fall frost November 19.

Where ZIP 31042 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone8b15 to 20 °F

Coldest night−9.4 to −6.7 °C

Last frostMar 12

First frostNov 19

2012 zone8a

Was 8a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Irwinton, GA…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Irwinton, GA

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMarch 12median — 50% chance of a later frost

Safe for tender plantsApril 1only 10% chance of frost after

First fall frostNovember 19median — 10% chance by Nov 3

Growing season255 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 25 and returns around December 4.

From the NOAA station Irwinton 4 Wnw, GA — 7 miles away, elevation 515 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 31042

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 29 – Feb 12

SpinachSow outdoors · Jan 29 – Feb 19

Broccoli, cabbageStart indoors · Jan 1 – Jan 15

Broccoli, cabbageTransplant · Feb 19 – Mar 5

Onion setsPlant outdoors · Feb 12 – Feb 26

PotatoesPlant outdoors · Feb 19 – Mar 5

LettuceSow outdoors · Feb 12 – Feb 26

Carrots, beetsSow outdoors · Feb 19 – Mar 5

TomatoesStart indoors · Jan 15 – Jan 29

TomatoesTransplant · Mar 19 – Apr 2

Peppers, eggplantStart indoors · Jan 1 – Jan 15

Peppers, eggplantTransplant · Mar 26 – Apr 9

BeansSow outdoors · Mar 19 – Apr 2

Sweet cornSow outdoors · Mar 19 – Apr 2

Cucumbers, squashSow outdoors · Mar 19 – Apr 2

Fall lettuce, spinachSow outdoors · Sep 24 – Oct 8

GarlicPlant cloves · Nov 5 – Dec 10

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 12) and first fall frost (Nov 19) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 31042 came on Feb 10 — 7 days later than the 1991–2020 average (Feb 3).

average
Feb 32026
Feb 10

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 8b in Georgia

590 plants native to the lower 48 states, recorded in Georgia, and rated by the USDA to survive 15 °F or colder — the bottom of zone 8b. Each links to its USDA PLANTS profile.

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Irwinton, GA.

Soil in Irwinton, GA

The soil mapped at the center of ZIP 31042 is Susquehanna — sandy loam, somewhat poorly drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH5.0strongly acidic; most vegetables like 6.0–7.0

DrainageSomewhat poorly drainedconsider raised beds

Organic matter1.25%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Susquehanna sandy loam, 5 to 12 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 31042; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Irwinton, GA

Summer high92 °Faverage high, July

Winter low36 °Faverage low, January

Hot days75days a year at 90 °F or more

Freezing nights35nights a year at 32 °F or less

Growing degree days5,881base 50 °F — the season’s usable heat

Longest day14 h 19 mindaylight on June 21

Shortest day9 h 59 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation46.8 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Irwinton 4 Wnw, GA (7 mi away); precipitation: Irwinton 4 Wnw, GA (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 8b.

Mc Intyre, GA · 10 mi

310038b

Allentown, GA · 10 mi

Jeffersonville, GA · 13 mi

310678b

Oconee, GA · 15 mi

Georgia planting zones →

Questions about 31042

What planting zone is ZIP code 31042?

ZIP code 31042 (Irwinton, GA) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in Irwinton, GA?

The median last spring frost (32 °F) near 31042 is March 12; after April 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Irwinton 4 Wnw station.

When is the first frost in Irwinton, GA?

The median first fall frost near 31042 is November 19, giving a median frost-free growing season of 255 days.

When should I plant tomatoes in 31042?

Start tomato seeds indoors around Jan 15 – Jan 29 and set transplants outside around Mar 19 – Apr 2, one to three weeks after the median last frost.

How much rain and snow does 31042 get?

About 46.8 inches of precipitation a year (NOAA 1991–2020 normals, Irwinton 4 Wnw station).

How hot do summers get in Irwinton, GA?

The average high peaks at 92 °F in July, with about 75 days a year at 90 °F or more.

What kind of soil does 31042 have?

The USDA soil survey maps Susquehanna at the center of ZIP 31042: sandy loam, somewhat poorly drained, pH about 5.0 (strongly acidic).

Did spring come early in Irwinton, GA in 2026?

Spring leaf-out near 31042 came on Feb 10 in 2026, 7 days later than the 1991–2020 average (Feb 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Irwinton, GA?

Intermediate onions: the longest day near 31042 is 14 h 19 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 31042 change?

Yes. The 2012 USDA map put 31042 in zone 8a; the 2023 map puts it in zone 8b. The newer map uses 1991–2020 data and more weather stations.