When to Plant Sweet Corn in Idaho
In Idaho, the time to sow sweet corn outside runs from Apr 13 – Apr 27 in Lewiston to May 30 – Jun 13 in Shelley. In Boise City, it's May 1 – May 15. The average last spring frost differs by about 7 weeks across the state (Apr 6 in Lewiston, May 23 in Shelley), so use the dates for the town nearest you.
Sow corn in blocks rather than single rows so it pollinates well. Wait for soil around 60°F.
- Sow outside: 1–3 weeks after the last frost.
Sweet Corn planting dates in Idaho by city
| City | Zone | Sow outside |
|---|---|---|
| Ammon | 5b | May 16 – May 30 |
| Blackfoot | 5b | May 12 – May 26 |
| Boise City | 7a | May 1 – May 15 |
| Burley | 6b | May 14 – May 28 |
| Caldwell | 7a | May 6 – May 20 |
| Chubbuck | 6b | May 23 – Jun 6 |
| Coeur d'Alene | 6b | Apr 29 – May 13 |
| Eagle | 7a | May 7 – May 21 |
| Emmett | 7a | May 7 – May 21 |
| Fruitland | 7a | Apr 29 – May 13 |
| Garden City | 7a | May 24 – Jun 7 |
| Hailey | 6a | May 20 – Jun 3 |
| Hayden | 6b | Apr 29 – May 13 |
| Idaho Falls | 5b | May 16 – May 30 |
| Jerome | 6b | May 9 – May 23 |
| Kimberly | 6b | May 13 – May 27 |
| Kuna | 7a | May 1 – May 15 |
| Lewiston | 7a | Apr 13 – Apr 27 |
| Meridian | 7a | May 1 – May 15 |
| Middleton | 7a | May 6 – May 20 |
| Moscow | 6b | May 6 – May 20 |
| Mountain Home | 7a | May 9 – May 23 |
| Nampa | 7a | May 6 – May 20 |
| Payette | 7a | Apr 26 – May 10 |
| Pocatello | 6a | May 9 – May 23 |
| Post Falls | 6b | Apr 29 – May 13 |
| Preston | 6a | May 23 – Jun 6 |
| Rathdrum | 6b | Apr 29 – May 13 |
| Rexburg | 5a | May 19 – Jun 2 |
| Rigby | 5b | May 16 – May 30 |
| Rupert | 6a | May 13 – May 27 |
| Sandpoint | 6b | May 15 – May 29 |
| Shelley | 5b | May 30 – Jun 13 |
| Star | 7a | May 6 – May 20 |
| Twin Falls | 7a | May 7 – May 21 |
| Weiser | 7a | Apr 30 – May 14 |
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 Idaho, or the general guide to when to plant sweet corn.
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