Denver, CO · zone 6a · ~164 frost-free days
When to plant in Denver: frost dates and zone 6a.
In Denver, the typical last spring frost lands around Apr 30 and the first fall frost around Oct 11, giving you about 164 frost-free days. Cool-season crops go out before the last frost; warm-season crops wait until after it.
The 2026 windows
Sow dates for Denver, keyed to your frost.
| Crop | Start indoors | Spring sow / set out | Fall sow |
|---|---|---|---|
| Tomato, slicing | Mar 26 to May 26 | May 7 to Jul 7 | — |
| Lettuce, leaf | — | Mar 23 to May 7 | Jul 28 to Sep 26 |
| Carrot | — | Mar 23 to Apr 25 | Jul 16 to Aug 11 |
| Bush Bean | — | Apr 30 to Jun 20 | Jun 27 to Jul 30 |
| Cucumber, slicing | — | May 7 to Jul 25 | — |
| Pepper, bell | Apr 4 to May 26 | May 16 to Jul 7 | — |
| Kale | Feb 9 to Mar 9 | Mar 23 to Apr 20 | Jul 11 to Aug 26 |
| Spinach | — | Mar 9 to Apr 20 | Jul 28 to Sep 15 |
Denver sits in Zone 6a, but two gardens in the same city can be a week or two apart. The planner works from your ZIP code's frost dates, not the zone, so the dates land right for your block, not the metro average.
Build your Denver garden plan.
Tell the free planner what you want to eat and who you're feeding. It returns plant counts, spacing, and frost-safe sow dates for ZIP 80202 in about 60 seconds.
Denver planting questions
What planting zone is Denver, CO?+
Denver is in USDA hardiness zone 6a. Growing zone, gardening zone, and planting zone all mean the same thing: the USDA number, 6a here. It tells you what survives winter, not when to plant. Frost dates set your planting time, and the free planner uses your exact ZIP code's frost dates, which can differ by weeks across one metro.
When is the last frost date in Denver?+
The typical last spring frost in Denver, CO is around Apr 30. That is an average from local history, not a guarantee, so tender crops like tomatoes and peppers are safer with a week of buffer after it.
When is the first frost date in Denver?+
The typical first fall frost in Denver, CO arrives around Oct 11, closing a growing season of roughly 164 frost-free days. Count backward from it to find the last date a fall crop can still finish.
What can I plant now in Denver?+
It depends on the date. Cool-season crops like lettuce, kale, and spinach go out weeks before the last frost; warm-season crops like tomatoes and peppers wait until after Apr 30. The table above shows each crop's window; the free planner turns your ZIP into an exact, dated calendar.