USDA zone 9a in North Carolina
USDA plant hardiness zone 9a covers 5 locations across North Carolina (average annual extreme minimum 20 to 25 °F): Buxton, NC, Grandy, NC, Harkers Island, NC, Kill Devil Hills, NC, Ocracoke, NC. Average last spring frost across this group ranges March 1 (Ocracoke) to March 28 (Grandy), and growing seasons run 230–293 days (Grandy to Ocracoke) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every North Carolina location's own frost dates; the printable planting calendar uses Kill Devil Hills, this group's median-season location.
- USDA zone
- 9a20 to 25 °F
- Last frost range
- Mar 1–Mar 28avg, 32°F
- First frost range
- Nov 12–Dec 22avg, 32°F
- Growing season range
- 230–293days
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) |
|---|---|---|---|---|---|
| Buxton | Frisco, Avon, Hatteras, Salvo, Waves | Cape Hatteras Ap | Mar 4 | Dec 22 | 290 |
| Grandy | Southern Shores | Elizabeth City Cgas | Mar 28 | Nov 12 | 230 |
| Harkers Island | Gloucester, Marshallberg | Beaufort Michael J Smith Fld | Mar 10 | Dec 1 | 265 |
| Kill Devil Hills * | Wanchese, Southern Shores, Manteo, Rodanthe | Manteo Ap | Mar 15 | Dec 6 | 266 |
| Ocracoke | — | Ocracoke | Mar 1 | Dec 20 | 293 |
* Kill Devil Hills 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 (Kill Devil Hills, representative)
Computed from Kill Devil Hills's average frost dates — the median-season location in this North 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 18 – Feb 1 | Mar 22 – Mar 29 | May 21 – Jun 10 | — | matures comfortably |
| Pepper | Very tender | Jan 4 – Jan 18 | Mar 29 – Apr 5 | May 28 – Jun 27 | — | matures comfortably |
| Cucumber | Tender | Feb 15 – Feb 22 | Mar 22 – Mar 29 | May 11 – May 31 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Mar 22 – Mar 29 | May 6 – May 21 | — | matures comfortably |
| Bush bean | Tender | — | Mar 22 – Mar 29 | May 11 – May 21 | Oct 7 – Oct 17 | matures comfortably |
| Sweet corn | Tender | — | Mar 15 – Mar 29 | May 14 – Jun 13 | — | matures comfortably |
| Basil | Very tender | Feb 1 – Feb 15 | Mar 22 – Mar 29 | Apr 21 – May 6 | — | matures comfortably |
| Lettuce | Half-hardy | Feb 1 – Feb 15 | Feb 15 – Mar 1 | Apr 1 – Apr 16 | Sep 23 – Oct 8 | matures comfortably |
| Pea | Hardy | — | Feb 1 – Feb 15 | Mar 28 – Apr 12 | Sep 13 – Sep 28 | matures comfortably |
| Spinach | Hardy | — | Feb 1 – Feb 15 | Mar 13 – Mar 23 | Oct 3 – Oct 13 | matures comfortably |
| Carrot | Half-hardy | — | Feb 22 – Mar 1 | Apr 23 – May 13 | Sep 3 – Sep 23 | matures comfortably |
| Broccoli | Half-hardy | Jan 18 – Feb 1 | Feb 15 – Mar 1 | Apr 11 – May 1 | Sep 8 – Sep 28 | matures comfortably |
Which crops fit this growing season
Using Kill Devil Hills's own 266-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 (Kill Devil Hills)
From NOAA's 1991–2020 Climate Normals at station USW00013766. 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 28 | Apr 12 | Nov 24 | Dec 10 | 241 |
| 32°F (freeze) | Mar 15 | Mar 30 | Dec 6 | Dec 27 | 266 |
| 28°F | Feb 28 | Mar 19 | Dec 25 | Jan 14 | 298 |
| 24°F | Feb 8 | Mar 5 | Jan 7 | Feb 2 | 327 |
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 5 locations is 5,330; Kill Devil Hills's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 4,991 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 8,077 | cool-season crops (brassicas, greens) |
Hardiness zone 9a in North 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. North Carolina spans 6 hardiness zones in this dataset — see all North Carolina locations for the full range, including zones6b, 7a, 7b, 8a, 8b.
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 North 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. 5 locations in North Carolina fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in North Carolina's zone 9a is the growing season longest?
- Ocracoke runs the longest season on this page at about 293 days; Grandy is shortest at about 230 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 North Carolina's zone 9a?
- Using Kill Devil Hills's frost dates (this page's median-season location): start seeds indoors about Jan 18 – Feb 1, then transplant outside about Mar 22 – Mar 29. 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 North 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 5 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.