When to plant in Denver, CO
USDA Zone 6aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Denver, Colorado — all computed from Denver's nearest NOAA weather station.
In zone 6a, Denver gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
DENVER-STAPLETON · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Denver’s own odds, recorded at DENVER-STAPLETON.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 26 | May 12 | May 2 | Sep 16 | Oct 1 | Oct 13 |
| 32°F | May 16 | May 4 | Apr 20 | Sep 25 | Oct 8 | Oct 20 |
| 28°F | May 7 | Apr 22 | Apr 6 | Oct 3 | Oct 18 | Oct 31 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Denver, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 16 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Denver planting FAQ
When is the last spring frost in Denver, CO?
On average, the last spring frost in Denver is around May 4 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Denver, CO?
In Denver, the first 32°F freeze of fall lands around October 8 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Denver in?
Denver is in USDA hardiness zone 6a. In zone 6a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Denver?
Denver has about 157 frost-free days — a moderate growing season — between the average last spring frost (May 4) and first fall frost (October 8).
When should I plant tomatoes in Denver?
For Denver, sow tomatoes indoors about March 9–March 23 and move the seedlings out around May 11, after the last spring frost.
Never miss a window in Denver
An email when it’s time to start seeds, transplant, and sow — timed to Denver’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Four Square Mile · 9 km
- Welby · 11 km
- Sherrelwood · 13 km
- Berkley · 14 km
- Aurora · 15 km
- Commerce City · 15 km
- Englewood · 16 km
- Federal Heights · 16 km
Frost dates recorded at DENVER-STAPLETON, 1 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Denver, CO — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00023062. Retrieved from https://blissgarden.com/colorado/denver.