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

Planting zone for 29455 — Johns Island, SC

ZIP code 29455 (Johns Island, Charleston County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 4 and the first fall frost December 30.

Where ZIP 29455 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.

Zone9a20 to 25 °F

Coldest night−6.7 to −3.9 °C

Last frostFeb 4

First frostDec 30

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 frostFebruary 4median — 50% chance of a later frost

Safe for tender plantsMarch 4only 10% chance of frost after

First fall frostDecember 30median — 10% chance by Dec 2

Growing season321 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 24 and returns around January 8.

From the NOAA station Charleston City, SC — 11 miles away, elevation 10 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 29455

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Dec 24 – Jan 7

SpinachSow outdoors · Dec 24 – Jan 14

Broccoli, cabbageStart indoors · Nov 26 – Dec 10

Broccoli, cabbageTransplant · Jan 14 – Jan 28

Onion setsPlant outdoors · Jan 7 – Jan 21

PotatoesPlant outdoors · Jan 14 – Jan 28

LettuceSow outdoors · Jan 7 – Jan 21

Carrots, beetsSow outdoors · Jan 14 – Jan 28

TomatoesStart indoors · Dec 10 – Dec 24

TomatoesTransplant · Feb 11 – Feb 25

Peppers, eggplantStart indoors · Nov 26 – Dec 10

Peppers, eggplantTransplant · Feb 18 – Mar 4

BeansSow outdoors · Feb 11 – Feb 25

Sweet cornSow outdoors · Feb 11 – Feb 25

Cucumbers, squashSow outdoors · Feb 11 – Feb 25

Fall lettuce, spinachSow outdoors · Nov 4 – Nov 18

GarlicPlant cloves · Dec 16 – Jan 20

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 4) and first fall frost (Dec 30) 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 29455 came on Feb 7 — 8 days later than the 1991–2020 average (Jan 30).

average
Jan 302026
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 29455 is Bohicket — silty clay loam, very poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up

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

DrainageVery poorly drainedconsider raised beds

Organic matter0.25%low — add compost

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Tidal marsh, soft.

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 29455; 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 high88 °Faverage high, July

Winter low44 °Faverage low, January

Hot days25days a year at 90 °F or more

Freezing nights6nights a year at 32 °F or less

Growing degree days6,519base 50 °F — the season’s usable heat

Longest day14 h 18 mindaylight on June 21

Shortest day10 h 00 mindaylight on December 21

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

Precipitation54.6 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 City, SC (11 mi away); precipitation: Johns Island 1.8 Ne, SC (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

294879a

Wadmalaw Island, SC · 6 mi

294579a

Johns Island, SC · 8 mi

294399a

Folly Beach, SC · 8 mi

294129a

Charleston, SC · 8 mi

294079a

Charleston, SC · 10 mi

294149a

Charleston, SC · 11 mi

294499a

Hollywood, SC · 11 mi

294019a

Charleston, SC · 11 mi

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

Questions about 29455

What planting zone is ZIP code 29455?

ZIP code 29455 (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 29455 is February 4; after March 4 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Charleston City station.

When is the first frost in Johns Island, SC?

The median first fall frost near 29455 is December 30, giving a median frost-free growing season of 321 days.

When should I plant tomatoes in 29455?

Start tomato seeds indoors around Dec 10 – Dec 24 and set transplants outside around Feb 11 – Feb 25, one to three weeks after the median last frost.

How much rain and snow does 29455 get?

About 54.6 inches of precipitation a year (NOAA 1991–2020 normals, Johns Island 1.8 Ne station).

How hot do summers get in Johns Island, SC?

The average high peaks at 88 °F in July, with about 25 days a year at 90 °F or more.

What kind of soil does 29455 have?

The USDA soil survey maps Bohicket at the center of ZIP 29455: silty clay loam, very poorly drained, pH about 4.7 (strongly acidic).

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

Spring leaf-out near 29455 came on Feb 7 in 2026, 8 days later than the 1991–2020 average (Jan 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Johns Island, SC?

Intermediate onions: the longest day near 29455 is 14 h 18 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 29455 change?

Yes. The 2012 USDA map put 29455 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.