Charleston, South Carolina: planting zone & frost dates
Charleston is in USDA plant hardiness zone 9a, where the average coldest winter night reaches 20 to 25°F (-6.7 to -3.9°C). The typical last spring frost is around Feb 17 and the first fall frost around Dec 20.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Mar 4 | Dec 2 |
| Typical planning date (30% risk) | Feb 17 | Dec 20 |
| Median (50%) | Feb 4 | Dec 30 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station CHARLESTON CITY, SC (USW00013782), 4.1 mi (6.6 km) from the city center and 7 ft higher than the city center (+2 m). Record used for the 1991–2020 normals: 30 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Charleston
All 8 ZIP codes covering Charleston are in zone 9a.
Vegetable planting calendar for Charleston
Dates are counted from the 30%-risk frost dates above (last frost Feb 17, first frost Dec 20). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Dec 23 – Jan 6 | Feb 24 – Mar 10 | — | — |
| Pepper | Dec 9 – Dec 23 | Mar 3 – Mar 17 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Jan 6 – Jan 20 | Feb 3 – Feb 24 | Jan 20 – Mar 3 | Oct 11 – Nov 8 |
| Green Beans | — | — | Feb 24 – Mar 31 | Sep 27 – Oct 11 |
| Sweet Corn | — | — | Feb 24 – Mar 24 | — |
| Zucchini & Summer Squash | Jan 20 – Jan 27 | Feb 24 – Mar 10 | Feb 24 – Mar 17 | Sep 27 – Oct 11 |
| Cucumber | Jan 20 – Jan 27 | Mar 3 – Mar 10 | Feb 24 – Mar 17 | Sep 27 – Oct 11 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 27 – Mar 3 | Sep 27 – Oct 11 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 25 – Dec 9 | Jan 20 – Feb 3 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Jan 20 – Feb 10 | — | — |
| Basil | Jan 6 – Jan 20 | Mar 3 – Mar 17 | Mar 3 – Mar 24 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 6 – Feb 3 | Oct 25 – Nov 22 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 23 – Jan 6 | Jan 20 – Feb 10 | Jan 20 – Feb 10 | Oct 11 – Nov 8 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 23 – Jan 6 | Feb 3 – Feb 24 | — | Sep 27 – Oct 11 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 6 – Jan 27 | Oct 11 – Oct 25 |
| Eggplant | Dec 9 – Dec 23 | Mar 3 – Mar 17 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 23 – Jan 6 | Jan 20 – Feb 3 | — | Sep 27 – Oct 11 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 13 – Mar 3 | Nov 8 – Dec 6 |
| Strawberry | — | Jan 20 – Feb 10 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 27 – Mar 10 | Oct 11 – Oct 25 |
Nearby cities in South Carolina
- Mount Pleasant — zone 9a, last frost Mar 21, first frost Nov 21
- North Charleston — zone 9a, last frost Mar 15, first frost Nov 19
- Columbia — zone 8b, last frost Mar 31, first frost Nov 9
More: all South Carolina cities · other zone 9a cities: San Antonio, TX, Austin, TX, Seattle, WA, Las Vegas, NV, Portland, OR, Tucson, AZ, Baton Rouge, LA, Tallahassee, FL
Charleston gardening questions
When is the last frost in Charleston, SC?
Plan around Feb 17. At NOAA's Charleston City, SC station, 4.1 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Feb 4, and after Mar 4 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Jan 24. Springs here are erratic: 58 days separate the 90% and 10% dates, versus a median of 36 days for cities on this site, so watch the forecast rather than the calendar.
When should I plant tomatoes in Charleston, SC?
Start seeds indoors Dec 23 – Jan 6 and set transplants outside Feb 24 – Mar 10, once nights stay above 50°F and the soil is near 60°F. With about 306 frost-free days, frost is not the main limit — fruit set drops when nights stay above about 75°F, so early plantings tend to do best. More: tomato planting dates by zone.
How long is the growing season in Charleston?
About 321 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 289 days, and in 1 year in 10 it runs 357 days or more. In fall there is a 10% chance of frost by Dec 2 and a 30% chance by Dec 20. That is the longest of the 4 South Carolina cities on this site.
When should I plant a fall garden in Charleston?
Count back from the first fall frost (Dec 20): transplant broccoli Sep 27 – Oct 11; sow kale Oct 11 – Nov 8; sow lettuce Oct 11 – Nov 8; sow radishes Nov 8 – Dec 6. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Jan 8. How the math works: succession and fall planting.
Did Charleston's hardiness zone change on the 2023 map?
Yes. Most of Charleston was zone 8b on the 2012 map and is zone 9a on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
How does Charleston compare with Mount Pleasant, SC?
Both are in zone 9a. The typical last spring frost in Charleston (Feb 17) comes about 32 days earlier than in Mount Pleasant, SC (Mar 21), 6 miles away, and the first fall frost is Dec 20 versus Nov 21. The two cities use different NOAA stations.