When to Plant Onions in North Dakota
In North Dakota, the time to plant onions outside runs from Apr 6 – Apr 20 in Fargo to Apr 23 – May 7 in Williston. In Fargo, it's Apr 6 – Apr 20. The average last spring frost differs by about 2 weeks across the state (May 4 in Fargo, May 21 in Williston), so use the dates for the town nearest you.
Onions are cold-hardy. Plant sets or transplants early so they grow leaves before long summer days trigger bulbing.
- Start indoors: 10–12 weeks before the last frost.
- Plant outside: 2–4 weeks before the last frost.
Onions planting dates in North Dakota by city
| City | Zone | Start indoors | Plant outside |
|---|---|---|---|
| Bismarck | 4a | Feb 15 – Mar 1 | Apr 12 – Apr 26 |
| Devils Lake | 4a | Feb 11 – Feb 25 | Apr 8 – Apr 22 |
| Dickinson | 4b | Feb 25 – Mar 11 | Apr 22 – May 6 |
| Fargo | 4a | Feb 9 – Feb 23 | Apr 6 – Apr 20 |
| Grand Forks | 4a | Feb 15 – Mar 1 | Apr 12 – Apr 26 |
| Horace | 4a | Feb 9 – Feb 23 | Apr 6 – Apr 20 |
| Jamestown | 4b | Feb 13 – Feb 27 | Apr 10 – Apr 24 |
| Mandan | 4a | Feb 18 – Mar 4 | Apr 15 – Apr 29 |
| Minot | 4a | Feb 15 – Mar 1 | Apr 12 – Apr 26 |
| Valley City | 4a | Feb 18 – Mar 4 | Apr 15 – Apr 29 |
| Wahpeton | 4a | Feb 9 – Feb 23 | Apr 6 – Apr 20 |
| Watford City | 4a | Feb 14 – Feb 28 | Apr 11 – Apr 25 |
| West Fargo | 4a | Feb 9 – Feb 23 | Apr 6 – Apr 20 |
| Williston | 4a | Feb 26 – Mar 12 | Apr 23 – May 7 |
Calculated from each town's average (50%) frost dates, from the nearest NOAA station (1991–2020). Typical dates for the 2027 planting season, based on NOAA's 1991–2020 averages. They are long-term odds, not a forecast: always check your local forecast before planting. Zones: 2023 USDA Plant Hardiness Zone Map (USDA-ARS and Oregon State University). Not the official map; see planthardiness.ars.usda.gov.
See all frost dates in North Dakota, or the general guide to when to plant onions.
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