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

Planting zone for 29457 — Johns Island, SC

ZIP code 29457 (Johns Island, Charleston County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 7 and the first fall frost November 27.

Where ZIP 29457 is

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.

Zone9a20 to 25 °F

Coldest night−6.7 to −3.9 °C

Last frostMar 7

First frostNov 27

2012 zone8b

Was 8b 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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Johns Island, 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 Johns Island, SC

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 7median — 50% chance of a later frost

Safe for tender plantsMarch 27only 10% chance of frost after

First fall frostNovember 27median — 10% chance by Nov 8

Growing season266 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 20 and returns around December 15.

From the NOAA station Charleston Intl Airport, SC — 8 miles away, elevation 39 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 29457

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 24 – Feb 7

SpinachSow outdoors · Jan 24 – Feb 14

Broccoli, cabbageStart indoors · Dec 27 – Jan 10

Broccoli, cabbageTransplant · Feb 14 – Feb 28

Onion setsPlant outdoors · Feb 7 – Feb 21

PotatoesPlant outdoors · Feb 14 – Feb 28

LettuceSow outdoors · Feb 7 – Feb 21

Carrots, beetsSow outdoors · Feb 14 – Feb 28

TomatoesStart indoors · Jan 10 – Jan 24

TomatoesTransplant · Mar 14 – Mar 28

Peppers, eggplantStart indoors · Dec 27 – Jan 10

Peppers, eggplantTransplant · Mar 21 – Apr 4

BeansSow outdoors · Mar 14 – Mar 28

Sweet cornSow outdoors · Mar 14 – Mar 28

Cucumbers, squashSow outdoors · Mar 14 – Mar 28

Fall lettuce, spinachSow outdoors · Oct 2 – Oct 16

GarlicPlant cloves · Nov 13 – Dec 18

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 7) and first fall frost (Nov 27) 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 29457 came on Feb 7 — 7 days later than the 1991–2020 average (Jan 31).

average
Jan 312026
Feb 7

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 9a in South Carolina

578 plants native to the lower 48 states, recorded in South Carolina, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. 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 Johns Island, SC.

Soil in Johns Island, SC

The soil mapped at the center of ZIP 29457 is Wadmalaw — fine sandy loam, poorly drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH4.7strongly acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter1.5%low — add compost

Hydrologic groupA/Ddrains fast once dried out; wet otherwise

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Wadmalaw 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 29457; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Johns Island, SC

Summer high91 °Faverage high, July

Winter low39 °Faverage low, January

Hot days64days a year at 90 °F or more

Freezing nights22nights a year at 32 °F or less

Growing degree days6,385base 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

Precipitation52.3 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: Charleston Intl Airport, SC (8 mi away); precipitation: Charleston 5.0 Wnw, SC (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

294149a

Charleston, SC · 3 mi

294709a

Ravenel, SC · 6 mi

294079a

Charleston, SC · 6 mi

294559a

Johns Island, SC · 8 mi

294049a

Charleston Afb, SC · 8 mi

294189a

North Charleston, SC · 8 mi

294059a

North Charleston, SC · 9 mi

294159a

North Charleston, SC · 9 mi

All 2 ZIP codes in Johns Island → · South Carolina planting zones →

Questions about 29457

What planting zone is ZIP code 29457?

ZIP code 29457 (Johns Island, SC) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Johns Island, SC?

The median last spring frost (32 °F) near 29457 is March 7; after March 27 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Charleston Intl Airport station.

When is the first frost in Johns Island, SC?

The median first fall frost near 29457 is November 27, giving a median frost-free growing season of 266 days.

When should I plant tomatoes in 29457?

Start tomato seeds indoors around Jan 10 – Jan 24 and set transplants outside around Mar 14 – Mar 28, one to three weeks after the median last frost.

How much rain and snow does 29457 get?

About 52.3 inches of precipitation a year (NOAA 1991–2020 normals, Charleston 5.0 Wnw station).

How hot do summers get in Johns Island, SC?

The average high peaks at 91 °F in July, with about 64 days a year at 90 °F or more.

What kind of soil does 29457 have?

The USDA soil survey maps Wadmalaw at the center of ZIP 29457: fine sandy loam, poorly drained, pH about 4.7 (strongly acidic).

Did spring come early in Johns Island, SC in 2026?

Spring leaf-out near 29457 came on Feb 7 in 2026, 7 days later than the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Johns Island, SC?

Intermediate onions: the longest day near 29457 is 14 h 19 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 29457 change?

Yes. The 2012 USDA map put 29457 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.