When to Plant Onions in Missouri
In Missouri, the time to plant onions outside runs from Mar 4 – Mar 18 in St. Louis to Mar 22 – Apr 5 in St. Joseph. In Kansas City, it's Mar 7 – Mar 21. The average last spring frost differs by about 3 weeks across the state (Apr 1 in St. Louis, Apr 19 in St. Joseph), 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 Missouri by city
| City | Zone | Start indoors | Plant outside |
|---|---|---|---|
| Arnold | 7a | Jan 15 – Jan 29 | Mar 12 – Mar 26 |
| Ballwin | 7a | Jan 10 – Jan 24 | Mar 7 – Mar 21 |
| Belton | 6b | Jan 19 – Feb 2 | Mar 16 – Mar 30 |
| Blue Springs | 6b | Jan 13 – Jan 27 | Mar 10 – Mar 24 |
| Cape Girardeau | 7a | Jan 11 – Jan 25 | Mar 8 – Mar 22 |
| Chesterfield | 7a | Jan 10 – Jan 24 | Mar 7 – Mar 21 |
| Columbia | 6b | Jan 11 – Jan 25 | Mar 8 – Mar 22 |
| Creve Coeur | 7a | Jan 10 – Jan 24 | Mar 7 – Mar 21 |
| Farmington | 6b | Jan 19 – Feb 2 | Mar 16 – Mar 30 |
| Florissant | 7a | Jan 8 – Jan 22 | Mar 5 – Mar 19 |
| Gladstone | 6b | Jan 10 – Jan 24 | Mar 7 – Mar 21 |
| Grandview | 6b | Jan 13 – Jan 27 | Mar 10 – Mar 24 |
| Hazelwood | 7a | Jan 8 – Jan 22 | Mar 5 – Mar 19 |
| Independence | 6b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Jefferson City | 6b | Jan 14 – Jan 28 | Mar 11 – Mar 25 |
| Joplin | 7a | Jan 15 – Jan 29 | Mar 12 – Mar 26 |
| Kansas City | 6b | Jan 10 – Jan 24 | Mar 7 – Mar 21 |
| Kirkwood | 7a | Jan 7 – Jan 21 | Mar 4 – Mar 18 |
| Lake St. Louis | 6b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Lee's Summit | 6b | Jan 13 – Jan 27 | Mar 10 – Mar 24 |
| Liberty | 6a | Jan 25 – Feb 8 | Mar 22 – Apr 5 |
| Maryland Heights | 7a | Jan 10 – Jan 24 | Mar 7 – Mar 21 |
| Nixa | 6b | Jan 21 – Feb 4 | Mar 18 – Apr 1 |
| O'Fallon | 6b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Ozark | 6b | Jan 21 – Feb 4 | Mar 18 – Apr 1 |
| Raymore | 6b | Jan 19 – Feb 2 | Mar 16 – Mar 30 |
| Raytown | 6b | Jan 13 – Jan 27 | Mar 10 – Mar 24 |
| Republic | 6b | Jan 15 – Jan 29 | Mar 12 – Mar 26 |
| Rolla | 6b | Jan 11 – Jan 25 | Mar 8 – Mar 22 |
| Sedalia | 6b | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Springfield | 7a | Jan 10 – Jan 24 | Mar 7 – Mar 21 |
| St. Charles | 6b | Jan 14 – Jan 28 | Mar 11 – Mar 25 |
| St. Joseph | 6a | Jan 25 – Feb 8 | Mar 22 – Apr 5 |
| St. Louis | 7a | Jan 7 – Jan 21 | Mar 4 – Mar 18 |
| St. Peters | 6b | Jan 15 – Jan 29 | Mar 12 – Mar 26 |
| University City | 7a | Jan 7 – Jan 21 | Mar 4 – Mar 18 |
| Warrensburg | 6b | Jan 20 – Feb 3 | Mar 17 – Mar 31 |
| Webster Groves | 7a | Jan 7 – Jan 21 | Mar 4 – Mar 18 |
| Wentzville | 6b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Wildwood | 7a | Jan 18 – Feb 1 | Mar 15 – Mar 29 |
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 Missouri, or the general guide to when to plant onions.
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