When to Plant Sweet Corn in Iowa
In Iowa, the time to sow sweet corn outside runs from Apr 22 – May 6 in Burlington to May 8 – May 22 in Spencer. In Des Moines, it's Apr 25 – May 9. The average last spring frost differs by about 2 weeks across the state (Apr 15 in Burlington, May 1 in Spencer), 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 Iowa by city
| City | Zone | Sow outside |
|---|---|---|
| Altoona | 5b | Apr 30 – May 14 |
| Ames | 5b | May 3 – May 17 |
| Ankeny | 5b | Apr 30 – May 14 |
| Bettendorf | 5b | Apr 23 – May 7 |
| Boone | 5a | May 5 – May 19 |
| Burlington | 6a | Apr 22 – May 6 |
| Cedar Falls | 5a | May 4 – May 18 |
| Cedar Rapids | 5b | May 4 – May 18 |
| Clinton | 5b | Apr 29 – May 13 |
| Clive | 5b | Apr 25 – May 9 |
| Coralville | 5b | Apr 28 – May 12 |
| Council Bluffs | 5b | Apr 25 – May 9 |
| Davenport | 5b | Apr 26 – May 10 |
| Des Moines | 5b | Apr 25 – May 9 |
| Dubuque | 5a | Apr 26 – May 10 |
| Fort Dodge | 5a | May 5 – May 19 |
| Grimes | 5b | Apr 26 – May 10 |
| Indianola | 5b | May 1 – May 15 |
| Iowa City | 5b | Apr 28 – May 12 |
| Johnston | 5b | Apr 26 – May 10 |
| Le Mars | 5a | May 7 – May 21 |
| Marion | 5a | May 5 – May 19 |
| Marshalltown | 5a | May 5 – May 19 |
| Mason City | 5a | May 6 – May 20 |
| Muscatine | 5b | May 1 – May 15 |
| Newton | 5b | Apr 29 – May 13 |
| North Liberty | 5b | Apr 28 – May 12 |
| Norwalk | 5b | Apr 25 – May 9 |
| Oskaloosa | 5b | Apr 28 – May 12 |
| Ottumwa | 5b | Apr 30 – May 14 |
| Pella | 5b | Apr 27 – May 11 |
| Pleasant Hill | 5b | Apr 25 – May 9 |
| Sioux City | 5a | May 6 – May 20 |
| Spencer | 5a | May 8 – May 22 |
| Storm Lake | 5a | May 2 – May 16 |
| Urbandale | 5b | Apr 26 – May 10 |
| Waterloo | 5a | May 4 – May 18 |
| Waukee | 5b | Apr 25 – May 9 |
| Waverly | 5a | May 4 – May 18 |
| West Des Moines | 5b | Apr 25 – May 9 |
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 Iowa, or the general guide to when to plant sweet corn.
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