When to plant · 27 cities · zones 7b–8b
When to plant onions in North Carolina
Start Spanish Onion seeds indoors around Jan 6 and transplant around Mar 3 — the North Carolina statewide median, counted from a last spring frost of Mar 31 across 853 ZIP codes and 185 NOAA stations.
The rule: Twelve weeks indoors, the earliest sowing on the calendar, then transplant about four weeks before the last frost.
24 of these North Carolina cities sit below 36° N, where a long-day onion never gets the day length to bulb. They are flagged in the table; plant a short-day type there.
North Carolina onions, by step
Statewide median last frost Mar 31, first fall frost Nov 4, 2027 season. Each cultivar's own indoor lead time and days to maturity, same engine as the Plan Builder.
| Cultivar | Start indoors | Plant out | First harvest | Days |
|---|---|---|---|---|
| Spanish OnionYellow Sweet Spanish (long-day) | Jan 6 | Mar 3 | Jun 21 | 110 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost. Statewide dates are the ZIP-weighted median of every NOAA 1991–2020 station North Carolina's ZIP codes resolve to.
Onions in North Carolina, city by city
Spanish Onion, scheduled from each city's nearest NOAA station — the same dates as its frost page.
| City | Last frost | Start indoors | Plant out | First harvest |
|---|---|---|---|---|
| Charlottezone 8abelow 36° N · short-day onion | Mar 30 | Jan 5 | Mar 2 | Jun 20 |
| Raleighzone 8abelow 36° N · short-day onion | Mar 28 | Jan 3 | Feb 28 | Jun 18 |
| Greensborozone 8a | Apr 1 | Jan 7 | Mar 4 | Jun 22 |
| Durhamzone 8abelow 36° N · short-day onion | Apr 2 | Jan 8 | Mar 5 | Jun 23 |
| Winston-Salemzone 8a | Mar 26 | Jan 1 | Feb 26 | Jun 16 |
| Fayettevillezone 8abelow 36° N · short-day onion | Mar 30 | Jan 5 | Mar 2 | Jun 20 |
| Caryzone 8abelow 36° N · short-day onion | Mar 27 | Jan 2 | Feb 27 | Jun 17 |
| Wilmingtonzone 8bbelow 36° N · short-day onion | Mar 19 | Dec 25 | Feb 19 | Jun 9 |
| High Pointzone 8abelow 36° N · short-day onion | Mar 30 | Jan 5 | Mar 2 | Jun 20 |
| Concordzone 8abelow 36° N · short-day onion | Apr 1 | Jan 7 | Mar 4 | Jun 22 |
| Greenvillezone 8abelow 36° N · short-day onion | Mar 27 | Jan 2 | Feb 27 | Jun 17 |
| Ashevillezone 7bbelow 36° N · short-day onion | Apr 6 | Jan 12 | Mar 9 | Jun 27 |
| Gastoniazone 8abelow 36° N · short-day onion | Mar 27 | Jan 2 | Feb 27 | Jun 17 |
| Apexzone 8abelow 36° N · short-day onion | Apr 6 | Jan 12 | Mar 9 | Jun 27 |
| Jacksonvillezone 8bbelow 36° N · short-day onion | Mar 23 | Dec 29 | Feb 23 | Jun 13 |
| Huntersvillezone 8abelow 36° N · short-day onion | Mar 30 | Jan 5 | Mar 2 | Jun 20 |
| Chapel Hillzone 8abelow 36° N · short-day onion | Mar 31 | Jan 6 | Mar 3 | Jun 21 |
| Burlingtonzone 8a | Apr 1 | Jan 7 | Mar 4 | Jun 22 |
| Kannapoliszone 8abelow 36° N · short-day onion | Apr 1 | Jan 7 | Mar 4 | Jun 22 |
| Wake Forestzone 8abelow 36° N · short-day onion | Apr 4 | Jan 10 | Mar 7 | Jun 25 |
| Rocky Mountzone 8abelow 36° N · short-day onion | Apr 1 | Jan 7 | Mar 4 | Jun 22 |
| Mooresvillezone 8abelow 36° N · short-day onion | Apr 9 | Jan 15 | Mar 12 | Jun 30 |
| Holly Springszone 8abelow 36° N · short-day onion | Mar 31 | Jan 6 | Mar 3 | Jun 21 |
| Wilsonzone 8abelow 36° N · short-day onion | Mar 22 | Dec 28 | Feb 22 | Jun 12 |
| Fuquay-Varinazone 8abelow 36° N · short-day onion | Apr 6 | Jan 12 | Mar 9 | Jun 27 |
| Hickoryzone 8abelow 36° N · short-day onion | Mar 31 | Jan 6 | Mar 3 | Jun 21 |
| Indian Trailzone 8abelow 36° N · short-day onion | Mar 31 | Jan 6 | Mar 3 | Jun 21 |
What these onions become
What North Carolina onions need
Yellow Sweet Spanish Onion Seed
A long-day storage onion with enough sugar to sweat down without scorching. The aromatic base under every tomato sauce on this site.
Organic Seed Starter Potting MixMust have
Seed-starting mix is not potting soil with a nicer label — it is finer, lighter, and low in nutrients on purpose, because a seedling's first roots want air and moisture, not fertiliser.
72-Cell Trays with 1020 Bottoms, 5-PackMust have
The cheap black nursery trays crack after one season and flex enough to break roots when you lift them. These do not. Over five seasons the price per use is lower than the throwaways.
T8 Full-Spectrum Grow Lights, 1 ft 4-packMust have
A south window in March delivers a fraction of the light a pepper seedling needs, and the plant tells you by stretching. Two inches of LED above the canopy for 16 hours a day fixes it permanently.
Rapitest Soil Test Kit
In-ground growers are guessing until they test. pH outside 6.0–6.8 locks nutrients out no matter how much fertiliser you add, and no amount of feeding fixes that.
Pure Organic Worm Castings, 15 lb
Not a fertiliser so much as a soil-biology inoculant with a mild nutrient charge. A cup in each planting hole is a cheap, unglamorous improvement you can measure by August.
Garden Harvest Basket with Tool Caddy
A harvest basket that doubles as a colander means the hose rinse happens in the garden, and the dirt stays outside. On a 20-pound tomato day that is a genuine time saving.
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Onions in North Carolina: questions
When should I plant onions in North Carolina?
Transplant around Mar 3 at the statewide median; across the state that date runs from Feb 22 in the warmest tenth of North Carolina's ZIP codes to Mar 22 in the coldest. To cut the freeze risk to one year in ten, count from Apr 16 instead of the median last frost. Use the city table for your own town.
When do I start onions seeds indoors in North Carolina?
Around Jan 6 for Spanish Onion: 12 weeks before the statewide median last frost, on soil held at 65–75 °F.
When is the last frost in North Carolina?
The ZIP-weighted median of NOAA 1991–2020 station medians is Mar 31. In the warmest tenth of North Carolina's ZIP codes the median last frost falls on or before Mar 22; in the coldest tenth, on or after Apr 19.
When will North Carolina onions be ready to harvest?
Spanish Onion planted on the statewide date is ready around Jun 21: 110 days from transplant.
Which onions grow in North Carolina?
Spanish Onion is a long-day onion: it bulbs at 14–16 hours of daylight, which it gets above roughly 36° N. 24 of the 27 North Carolina cities listed here sit below that line; grow a short-day onion there.
More for North Carolina
- When to plant tomatoes
- When to plant peppers
- When to plant tomatillos
- When to plant basil
- When to plant cilantro
- When to plant carrots
- When to plant mustard greens
Onions in every state → · North Carolina frost dates → · How frost-date math works →