When to Plant Tomatoes in Colorado
In Colorado, the time to transplant tomatoes 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.
Tomatoes are killed by frost and sulk in cold soil. Wait until nights stay above 50°F, usually one to three weeks after the average last frost.
- Start indoors: 6–8 weeks before the last frost.
- Transplant outside: 1–3 weeks after the last frost.
Tomatoes planting dates in Colorado by city
| City | Zone | Start indoors | Transplant outside |
|---|---|---|---|
| Arvada | 6a | Mar 10 – Mar 24 | May 12 – May 26 |
| Aurora | 6a | Mar 12 – Mar 26 | May 14 – May 28 |
| Boulder | 6a | Mar 11 – Mar 25 | May 13 – May 27 |
| Brighton | 5b | Mar 8 – Mar 22 | May 10 – May 24 |
| Broomfield | 6a | Mar 7 – Mar 21 | May 9 – May 23 |
| Castle Pines | 5b | Mar 14 – Mar 28 | May 16 – May 30 |
| Castle Rock | 5b | Mar 14 – Mar 28 | May 16 – May 30 |
| Cañon City | 6a | Mar 9 – Mar 23 | May 11 – May 25 |
| Centennial | 6a | Mar 10 – Mar 24 | May 12 – May 26 |
| Colorado Springs | 6a | Mar 8 – Mar 22 | May 10 – May 24 |
| Commerce City | 6a | Mar 8 – Mar 22 | May 10 – May 24 |
| Denver | 6a | Mar 9 – Mar 23 | May 11 – May 25 |
| Durango | 6b | Mar 26 – Apr 9 | May 28 – Jun 11 |
| Englewood | 6a | Mar 7 – Mar 21 | May 9 – May 23 |
| Erie | 5b | Mar 12 – Mar 26 | May 14 – May 28 |
| Evans | 5b | Mar 7 – Mar 21 | May 9 – May 23 |
| Firestone | 5b | Mar 12 – Mar 26 | May 14 – May 28 |
| Fort Collins | 5b | Mar 7 – Mar 21 | May 9 – May 23 |
| Fountain | 6a | Mar 8 – Mar 22 | May 10 – May 24 |
| Frederick | 5b | Mar 12 – Mar 26 | May 14 – May 28 |
| Golden | 5b | Mar 8 – Mar 22 | May 10 – May 24 |
| Grand Junction | 7a | Feb 17 – Mar 3 | Apr 21 – May 5 |
| Greeley | 5b | Mar 7 – Mar 21 | May 9 – May 23 |
| Greenwood Village | 6a | Mar 12 – Mar 26 | May 14 – May 28 |
| Johnstown | 5b | Mar 15 – Mar 29 | May 17 – May 31 |
| Lafayette | 6a | Mar 7 – Mar 21 | May 9 – May 23 |
| Lakewood | 6a | Mar 8 – Mar 22 | May 10 – May 24 |
| Littleton | 6a | Mar 7 – Mar 21 | May 9 – May 23 |
| Lone Tree | 6a | Mar 10 – Mar 24 | May 12 – May 26 |
| Longmont | 5b | Mar 12 – Mar 26 | May 14 – May 28 |
| Louisville | 6a | Mar 11 – Mar 25 | May 13 – May 27 |
| Loveland | 5b | Mar 15 – Mar 29 | May 17 – May 31 |
| Montrose | 6b | Mar 3 – Mar 17 | May 5 – May 19 |
| Northglenn | 6a | Mar 7 – Mar 21 | May 9 – May 23 |
| Parker | 5b | Mar 14 – Mar 28 | May 16 – May 30 |
| Pueblo | 6a | Mar 5 – Mar 19 | May 7 – May 21 |
| Thornton | 6a | Mar 7 – Mar 21 | May 9 – May 23 |
| Westminster | 6a | Mar 7 – Mar 21 | May 9 – May 23 |
| Wheat Ridge | 6a | Mar 10 – Mar 24 | May 12 – May 26 |
| Windsor | 5b | Mar 8 – Mar 22 | 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 tomatoes.
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