Frost dates for Aspen, CO
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
June 2
typical year
Safe to plant
June 17
frost is over in 9 of 10 years
First fall frost
September 23
typical year
Growing season
113 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | May 5 – 19 | – |
| Spinach | – | Apr 21 – May 12 | Jul 29 – Aug 12 |
| Lettuce | – | May 5 – 26 | Jul 29 – Aug 12 |
| Radishes | – | May 5 – Jun 16 | Aug 12 – 26 |
| Onions | – | May 5 – 19 | – |
| Potatoes | – | May 12 – 26 | – |
| Carrots | – | May 12 – Jun 2 | Jul 1 – 15 |
| Beets | – | May 5 – 19 | Jul 15 – 29 |
| Kale | Mar 24 – Apr 7 | May 5 – 19 | Jul 15 – 29 |
| Broccoli | Mar 24 – Apr 7 | May 19 – Jun 2 | Jul 15 – 29 |
| Cabbage | Mar 10 – 24 | May 5 – 19 | Jul 15 – 29 |
| Garlic | – | – | Aug 12 – Sep 2 |
| Warm-season crops | |||
| Tomatoes | Apr 22 – May 6 | Jun 17 – Jul 1 | – |
| Peppers | Apr 15 – 29 | Jun 24 – Jul 8 | – |
| Cucumbers | – | Jun 17 – Jul 8 | – |
| Zucchini | – | Jun 17 – Jul 15 | – |
| Pumpkins | Season usually too short. Try a quick variety or row covers. | ||
| Green beans | – | Jun 17 – Jul 15 | – |
| Sweet corn | – | Jun 17 – Jul 15 | – |
| Basil | May 13 – 27 | Jun 24 – Jul 1 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | June 17 | June 2 | May 17 |
| Fall frost before | September 12 | September 23 | October 4 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around May 18 (June 5 in a late year), and the first one in fall around October 1.
Towns that use these dates
This is the nearest NOAA station with frost records for 1 town.
Aspen
Where these dates come from
NOAA weather station ASPEN 1SW, CO US (USC00050372), 1991–2020 climate normals. It's the nearest station for 4 zip codes, all within 18 miles:
81225, 81611, 81612, 81642
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.