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

Planting zone for 29474 — Round O, SC

ZIP code 29474 (Round O, Colleton County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 19 and the first fall frost November 12.

Where ZIP 29474 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 19
First frostNov 12
2012 zone8b

Same zone as on the 2012 map. 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 Round O, SC…

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 Round O, SC

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 19median — 50% chance of a later frost
Safe for tender plantsApril 9only 10% chance of frost after
First fall frostNovember 12median — 10% chance by Oct 29
Growing season239 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 1 and returns around November 28.

From the NOAA station Walterboro 1 Sw, SC — 9 miles away, elevation 56 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 29474

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 5 – Feb 19
SpinachSow outdoors · Feb 5 – Feb 26
Broccoli, cabbageStart indoors · Jan 8 – Jan 22
Broccoli, cabbageTransplant · Feb 26 – Mar 12
Onion setsPlant outdoors · Feb 19 – Mar 5
PotatoesPlant outdoors · Feb 26 – Mar 12
LettuceSow outdoors · Feb 19 – Mar 5
Carrots, beetsSow outdoors · Feb 26 – Mar 12
TomatoesStart indoors · Jan 22 – Feb 5
TomatoesTransplant · Mar 26 – Apr 9
Peppers, eggplantStart indoors · Jan 8 – Jan 22
Peppers, eggplantTransplant · Apr 2 – Apr 16
BeansSow outdoors · Mar 26 – Apr 9
Sweet cornSow outdoors · Mar 26 – Apr 9
Cucumbers, squashSow outdoors · Mar 26 – Apr 9
Fall lettuce, spinachSow outdoors · Sep 17 – Oct 1
GarlicPlant cloves · Oct 29 – Dec 3
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 19) and first fall frost (Nov 12) 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 29474 came on Feb 14 — 14 days later than the 1991–2020 average (Jan 31).

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).

Soil in Round O, SC

The soil mapped at the center of ZIP 29474 is Bladen — fine sandy loam, poorly drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH4.6strongly acidic; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter2%moderate
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Bladen fine sandy loam.

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 29474; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Round O, SC

Summer high91 °Faverage high, July
Winter low35 °Faverage low, January
Hot days67days a year at 90 °F or more
Freezing nights44nights a year at 32 °F or less
Growing degree days5,657base 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
Precipitation56 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 58 °F, low 35 °F 58°35° JanFebruary: average high 62 °F, low 38 °F 62°38° FebMarch: average high 69 °F, low 44 °F 69°44° MarApril: average high 76 °F, low 50 °F 76°50° AprMay: average high 83 °F, low 60 °F 83°60° MayJune: average high 87 °F, low 68 °F 87°68° JunJuly: average high 91 °F, low 71 °F 91°71° JulAugust: average high 89 °F, low 70 °F 89°70° AugSeptember: average high 84 °F, low 65 °F 84°65° SepOctober: average high 76 °F, low 53 °F 76°53° OctNovember: average high 68 °F, low 42 °F 68°42° NovDecember: average high 61 °F, low 38 °F 61°38° Dec

Precipitation by month inches

0″2″4″6″8″January: 3.71 in precipitation 3.7 JanFebruary: 3.72 in precipitation 3.7 FebMarch: 4.02 in precipitation 4.0 MarApril: 3.24 in precipitation 3.2 AprMay: 3.65 in precipitation 3.6 MayJune: 6.45 in precipitation 6.5 JunJuly: 6.48 in precipitation 6.5 JulAugust: 8.54 in precipitation 8.5 AugSeptember: 5.65 in precipitation 5.7 SepOctober: 3.95 in precipitation 4.0 OctNovember: 2.85 in precipitation 2.9 NovDecember: 3.76 in precipitation 3.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Walterboro 1 Sw, SC (9 mi away); precipitation: Cottageville 5.8 Wsw, SC (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

2 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

294358b
Cottageville, SC · 5 mi
294888b
Walterboro, SC · 9 mi
294269a
Adams Run, SC · 13 mi
294338b
Canadys, SC · 13 mi
294529a
Jacksonboro, SC · 13 mi
294478b
Grover, SC · 15 mi
294728b
Ridgeville, SC · 16 mi
294378b
Dorchester, SC · 17 mi

South Carolina planting zones →

Questions about 29474

What planting zone is ZIP code 29474?

ZIP code 29474 (Round O, SC) 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 Round O, SC?

The median last spring frost (32 °F) near 29474 is March 19; after April 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Walterboro 1 Sw station.

When is the first frost in Round O, SC?

The median first fall frost near 29474 is November 12, giving a median frost-free growing season of 239 days.

When should I plant tomatoes in 29474?

Start tomato seeds indoors around Jan 22 – Feb 5 and set transplants outside around Mar 26 – Apr 9, one to three weeks after the median last frost.

How much rain and snow does 29474 get?

About 56 inches of precipitation a year (NOAA 1991–2020 normals, Cottageville 5.8 Wsw station).

How hot do summers get in Round O, SC?

The average high peaks at 91 °F in July, with about 67 days a year at 90 °F or more.

What kind of soil does 29474 have?

The USDA soil survey maps Bladen at the center of ZIP 29474: fine sandy loam, poorly drained, pH about 4.6 (strongly acidic).

Did spring come early in Round O, SC in 2026?

Spring leaf-out near 29474 came on Feb 14 in 2026, 14 days later than the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Round O, SC?

Intermediate onions: the longest day near 29474 is 14 h 19 min, so day-neutral types bulb best; long-day varieties may not bulb fully.