When to Plant Sweet Corn in Colorado
In Colorado, the time to sow sweet corn outside runs from Apr 21 – May 5 in Grand Junction to May 28 – Jun 11 in Durango. In Denver, it's May 11 – May 25. The average last spring frost differs by about 5 weeks across the state (Apr 14 in Grand Junction, May 21 in Durango), 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 Colorado by city
| City | Zone | Sow outside |
|---|---|---|
| Arvada | 6a | May 12 – May 26 |
| Aurora | 6a | May 14 – May 28 |
| Boulder | 6a | May 13 – May 27 |
| Brighton | 5b | May 10 – May 24 |
| Broomfield | 6a | May 9 – May 23 |
| Castle Pines | 5b | May 16 – May 30 |
| Castle Rock | 5b | May 16 – May 30 |
| Cañon City | 6a | May 11 – May 25 |
| Centennial | 6a | May 12 – May 26 |
| Colorado Springs | 6a | May 10 – May 24 |
| Commerce City | 6a | May 10 – May 24 |
| Denver | 6a | May 11 – May 25 |
| Durango | 6b | May 28 – Jun 11 |
| Englewood | 6a | May 9 – May 23 |
| Erie | 5b | May 14 – May 28 |
| Evans | 5b | May 9 – May 23 |
| Firestone | 5b | May 14 – May 28 |
| Fort Collins | 5b | May 9 – May 23 |
| Fountain | 6a | May 10 – May 24 |
| Frederick | 5b | May 14 – May 28 |
| Golden | 5b | May 10 – May 24 |
| Grand Junction | 7a | Apr 21 – May 5 |
| Greeley | 5b | May 9 – May 23 |
| Greenwood Village | 6a | May 14 – May 28 |
| Johnstown | 5b | May 17 – May 31 |
| Lafayette | 6a | May 9 – May 23 |
| Lakewood | 6a | May 10 – May 24 |
| Littleton | 6a | May 9 – May 23 |
| Lone Tree | 6a | May 12 – May 26 |
| Longmont | 5b | May 14 – May 28 |
| Louisville | 6a | May 13 – May 27 |
| Loveland | 5b | May 17 – May 31 |
| Montrose | 6b | May 5 – May 19 |
| Northglenn | 6a | May 9 – May 23 |
| Parker | 5b | May 16 – May 30 |
| Pueblo | 6a | May 7 – May 21 |
| Thornton | 6a | May 9 – May 23 |
| Westminster | 6a | May 9 – May 23 |
| Wheat Ridge | 6a | May 12 – May 26 |
| Windsor | 5b | May 10 – May 24 |
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 Colorado, or the general guide to when to plant sweet corn.
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