Planting dates for Denver
Frost dates and sow windows from the 30-year record at Ralston Rsvr, the official station 23 km from Denver, Colorado.
Sow and transplant events for the staples, straight from this page.
Key windows for Denver (2026)
| Crop | Start indoors | Plant out / sow |
|---|---|---|
| Tomato | March 22 | May 10 |
| Pepper | March 8 | May 17 |
| Peas | – | March 29 |
| Lettuce | March 8 | April 5 |
| Carrot | – | April 12 |
| Bush beans | – | May 10 |
| Garlic (longer than the average season; use short varieties) | – | Fall planted |
| Potato | – | April 19 |
Mean-date planning windows, not guarantees; watch the local forecast at the shoulders. Method on the methodology page.
Denver planting questions
When is the last frost in Denver?
Around May 3, the 30-year mean date of the last spring frost at Ralston Rsvr, the official station 23 km from Denver. Half of years see frost after the mean, so tender crops usually wait a week or more past it.
When can I plant tomatoes in Denver?
Start seeds indoors around March 22 and transplant around May 10, once nights hold above 50F. The full 32-crop table on the planner computes every window for Denver.
How long is the growing season in Denver?
About 161 frost-free days on average, from roughly May 3 to October 14. Crops whose days-to-maturity exceed that window need transplants, short-season varieties, or season extension.
How this page was made
Every date above is computed from the NOAA NCEI U.S. Climate Normals at Ralston Rsvr: the 30-year mean dates of last spring and first fall frost, with crop offsets from standard horticultural practice. Full method and crop sources: data and methodology. These are planning averages, not forecasts: half of years frost later than the mean, so harden off transplants and watch the local forecast at the shoulders of the season.
More for Denver: winter tire dates. Need every crop, or a different place? The full calendar covers 32 crops at 2697 stations.