USDA zone 9a in South Carolina
USDA plant hardiness zone 9a covers 7 locations across South Carolina (average annual extreme minimum 20 to 25 °F): Charleston, SC, Charleston, SC, Gillisonville, SC, Jacksonboro, SC, McClellanville, SC, Meggett, SC, and 1 more. Average last spring frost across this group ranges February 4 (Charleston) to March 23 (Gillisonville), and growing seasons run 233–321 days (Gillisonville to Charleston) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every South Carolina location's own frost dates; the printable planting calendar uses McClellanville, this group's median-season location.
- USDA zone
- 9a20 to 25 °F
- Last frost range
- Feb 4–Mar 23avg, 32°F
- First frost range
- Nov 6–Dec 30avg, 32°F
- Growing season range
- 233–321days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Charleston | Mount Pleasant, Awendaw, Folly Beach, Kiawah Island, James Island, Isle of Palms | Charleston City | Feb 4 | Dec 30 | 321 |
| Charleston | North Charleston, Mount Pleasant, Ravenel | Charleston Intl Ap | Mar 7 | Nov 27 | 266 |
| Gillisonville | — | Yemassee 1 N | Mar 23 | Nov 6 | 233 |
| Jacksonboro | — | Walterboro 1 Sw | Mar 19 | Nov 12 | 239 |
| McClellanville * | — | Mcclellanville 7 Ne | Feb 28 | Dec 1 | 277 |
| Meggett | Edisto Beach, Adams Run, Rockville | Edisto Is Middleton Plantation | Mar 1 | Dec 6 | 284 |
| Ridgeland | Beaufort, Port Royal, Seabrook, Shell Point, Dale | Beaufort Mcas | Feb 28 | Dec 3 | 279 |
* McClellanville is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (McClellanville, representative)
Computed from McClellanville's average frost dates — the median-season location in this South Carolinazone 9a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Jan 3 – Jan 17 | Mar 7 – Mar 14 | May 6 – May 26 | — | matures comfortably |
| Pepper | Very tender | Jan 1 – Jan 3 | Mar 14 – Mar 21 | May 13 – Jun 12 | — | matures comfortably |
| Cucumber | Tender | Jan 31 – Feb 7 | Mar 7 – Mar 14 | Apr 26 – May 16 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Mar 7 – Mar 14 | Apr 21 – May 6 | — | matures comfortably |
| Bush bean | Tender | — | Mar 7 – Mar 14 | Apr 26 – May 6 | Oct 2 – Oct 12 | matures comfortably |
| Sweet corn | Tender | — | Feb 28 – Mar 14 | Apr 29 – May 29 | — | matures comfortably |
| Basil | Very tender | Jan 17 – Jan 31 | Mar 7 – Mar 14 | Apr 6 – Apr 21 | — | matures comfortably |
| Lettuce | Half-hardy | Jan 17 – Jan 31 | Jan 31 – Feb 14 | Mar 17 – Apr 1 | Sep 18 – Oct 3 | matures comfortably |
| Pea | Hardy | — | Jan 17 – Jan 31 | Mar 13 – Mar 28 | Sep 8 – Sep 23 | matures comfortably |
| Spinach | Hardy | — | Jan 17 – Jan 31 | Feb 26 – Mar 8 | Sep 28 – Oct 8 | matures comfortably |
| Carrot | Half-hardy | — | Feb 7 – Feb 14 | Apr 8 – Apr 28 | Aug 29 – Sep 18 | matures comfortably |
| Broccoli | Half-hardy | Jan 3 – Jan 17 | Jan 31 – Feb 14 | Mar 27 – Apr 16 | Sep 3 – Sep 23 | matures comfortably |
Which crops fit this growing season
Using McClellanville's own 277-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (McClellanville)
From NOAA's 1991–2020 Climate Normals at station USW00003728. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | Mar 19 | Apr 6 | Nov 15 | Dec 6 | 246 |
| 32°F (freeze) | Feb 28 | Mar 25 | Dec 1 | Dec 31 | 277 |
| 28°F | Feb 6 | Mar 9 | Dec 25 | Jan 23 | 312 |
| 24°F | Jan 25 | Feb 24 | Jan 7 | Feb 1 | 345 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 7 locations is 6,385; McClellanville's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 5,918 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 9,245 | cool-season crops (brassicas, greens) |
Hardiness zone 9a in South Carolina
Zone 9a means an average annual extreme minimum winter temperature of about 20 to 25 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. South Carolina spans 5 hardiness zones in this dataset — see all South Carolina locations for the full range, including zones7b, 8a, 8b, 9b.
Explore zone 9a in other states at zone 9a, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 9a mean in South Carolina?
- Zone 9a means an average annual extreme minimum winter temperature of 20 to 25 °F — the standard USDA measure of which perennials survive winter. 7 locations in South Carolina fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in South Carolina's zone 9a is the growing season longest?
- Charleston runs the longest season on this page at about 321 days; Gillisonville is shortest at about 233 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in South Carolina's zone 9a?
- Using McClellanville's frost dates (this page's median-season location): start seeds indoors about Jan 3 – Jan 17, then transplant outside about Mar 7 – Mar 14. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in South Carolina's zone 9a have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 7 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.