Harkers Island, NC planting calendar
- USDA zone
- 9a20 to 25 °F
- Last frost
- Mar 10avg, 32°F
- First frost
- Dec 1avg, 32°F
- Growing season
- 265days
Harkers Island, North Carolina is in USDA plant hardiness zone 9a. Its average last spring frost is around March 10 and the first fall frost around December 1, giving a growing season of about 265 days (NOAA 1991–2020 normals, 32°F, median). Start tender crops like tomatoes and peppers indoors weeks before the last frost and set them out afterward; sow hardy crops such as peas, spinach, and lettuce before it. The planner below turns those frost dates into a printable per-crop planting calendar.
Harkers Island planting calendar
Each crop's windows are counted from Harkers Island's average frost dates. 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.
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting |
|---|---|---|---|---|---|
| Tomato | Tender | Jan 13 – Jan 27 | Mar 17 – Mar 24 | May 16 – Jun 5 | — |
| Pepper | Very tender | Jan 1 – Jan 13 | Mar 24 – Mar 31 | May 23 – Jun 22 | — |
| Cucumber | Tender | Feb 10 – Feb 17 | Mar 17 – Mar 24 | May 6 – May 26 | — |
| Summer squash / zucchini | Tender | — | Mar 17 – Mar 24 | May 1 – May 16 | — |
| Bush bean | Tender | — | Mar 17 – Mar 24 | May 6 – May 16 | Oct 2 – Oct 12 |
| Sweet corn | Tender | — | Mar 10 – Mar 24 | May 9 – Jun 8 | — |
| Basil | Very tender | Jan 27 – Feb 10 | Mar 17 – Mar 24 | Apr 16 – May 1 | — |
| Lettuce | Half-hardy | Jan 27 – Feb 10 | Feb 10 – Feb 24 | Mar 27 – Apr 11 | Sep 18 – Oct 3 |
| Pea | Hardy | — | Jan 27 – Feb 10 | Mar 23 – Apr 7 | Sep 8 – Sep 23 |
| Spinach | Hardy | — | Jan 27 – Feb 10 | Mar 8 – Mar 18 | Sep 28 – Oct 8 |
| Carrot | Half-hardy | — | Feb 17 – Feb 24 | Apr 18 – May 8 | Aug 29 – Sep 18 |
| Broccoli | Half-hardy | Jan 13 – Jan 27 | Feb 10 – Feb 24 | Apr 6 – Apr 26 | Sep 3 – Sep 23 |
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.
Frost & freeze dates
From NOAA's 1991–2020 Climate Normals at station USW00093765. 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 (p10 for spring, p90 for fall) — 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 21 | Apr 6 | Nov 15 | Dec 4 | 239 |
| 32°F (freeze) | Mar 10 | Mar 26 | Dec 1 | Dec 24 | 265 |
| 28°F | Feb 23 | Mar 16 | Dec 17 | Jan 13 | 296 |
| 24°F | Feb 2 | Mar 3 | Jan 4 | Jan 30 | 329 |
32°F is the standard "freeze" line that damages tender crops; lighter 36°F frost can nip the most cold-sensitive plants, while hardy crops shrug off light frost down toward 28°F. Use the threshold that matches what you are protecting.
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. Warm-season crops need a long, warm GDD total; a short, cool GDD total favors greens and brassicas.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 5,580 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 8,809 | cool-season crops (brassicas, greens) |
Hardiness zone 9a
Harkers Island sits in USDA plant hardiness zone 9a on the 2023 map — meaning its average annual extreme minimum winter temperature is about 20 to 25 °F. That number 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.
Explore more places in zone 9a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Harkers Island?
- Harkers Island, North Carolina is in USDA plant hardiness zone 9a on the 2023 map (average annual extreme minimum temperature 20 to 25 °F) — from the USDA Plant Hardiness Zone Map 2023, matched to this location's ZIP. See the methodology page for sources.
- When is the last frost in Harkers Island?
- The average (median) last spring frost at 32°F is around March 10, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as March 26, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Harkers Island?
- The average first fall frost at 32°F is around December 1. That leaves a growing season of about 265 days between the average last spring and first fall frosts.
- When should I start tomatoes in Harkers Island?
- Start tomato seeds indoors about Jan 13 – Jan 27 and transplant them outside about Mar 17 – Mar 24, once the danger of frost has passed. Estimated first harvest is around May 16 – Jun 5.
- How long is the growing season in Harkers Island?
- About 265 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~March 10) and the average first fall frost (~December 1). Cold-hardy crops extend usable time at both ends; frost-tender crops fit inside it.
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020 for station USW00093765 (Beaufort Michael J Smith Fld, 10.4 km away). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to this 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.