Frost dates for 81612 — Aspen, CO
Last spring frostMay 31median date
First fall frostSep 23median date
Growing season115 daysfrost-free
Hardiness zone5aZone 5a
How Aspen compares
- In 8 years out of 10, the last spring frost in Aspen falls between May 16 and June 14, a 29-day window. The first fall frost falls between September 11 and October 3.
- The median last frost is 20 days later than the Colorado median of May 11.
- Its 115-day growing season is longer than 23% of the 374 Colorado places with a regular frost season (state median 146 days).
- The last frost is 28 days later than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 212 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 16 |
| 50% (median) | May 31 |
| 10% (safe for tender plants) | June 14 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 11 |
| 50% (median) | September 23 |
| 90% (late) | October 3 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Aspen, CO
Frost dates for 81612 — Aspen, CO — last frost May 31, first frost Sep 23, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Mar 8 to Mar 22Transplant outside: May 3 to May 17
Start indoors: Mar 22 to Apr 5Transplant outside: Jun 14 to Jun 28
Start indoors: Mar 22 to Apr 5Transplant outside: Jun 14 to Jun 28
Start indoors: Apr 5 to Apr 19Transplant outside: Jun 7 to Jun 21
Start indoors: Apr 5 to Apr 19Transplant outside: May 10 to May 24Sow outdoors: May 3 to Jun 7Plant for fall: Jul 29 to Aug 26
Start indoors: Apr 5 to Apr 19Transplant outside: May 3 to May 17Sow outdoors: May 3 to May 17Plant for fall: Jul 15 to Aug 5
Start indoors: Apr 5 to Apr 19Transplant outside: May 17 to May 31Plant for fall: Jun 17 to Jul 8
Start indoors: Apr 5 to Apr 19Transplant outside: May 10 to May 24Plant for fall: Jun 17 to Jul 8
Start indoors: Apr 5 to Apr 19Transplant outside: May 17 to May 31Plant for fall: Jun 17 to Jul 8
Start indoors: Apr 19 to May 3Transplant outside: Jun 21 to Jul 5Sow outdoors: Jun 21 to Jul 5
Start indoors: Apr 19 to May 3Transplant outside: Jun 7 to Jun 21
Sow outdoors: Apr 19 to May 10Plant for fall: Jul 1 to Jul 22
Sow outdoors: Apr 19 to May 10Plant for fall: Jul 29 to Aug 19
Sow outdoors: Apr 26 to Jun 7Plant for fall: Aug 12 to Sep 2
Start indoors: May 3 to May 10Transplant outside: Jun 14 to Jun 21Sow outdoors: Jun 7 to Jun 21Plant for fall: Jul 8 to Jul 22
Start indoors: May 3 to May 10Sow outdoors: Jun 7 to Jun 21Plant for fall: Jul 15 to Jul 29
Start indoors: May 3 to May 10Sow outdoors: Jun 7 to Jun 21
Start indoors: May 3 to May 10Transplant outside: Jun 14 to Jun 28
Sow outdoors: May 10 to Jun 7Plant for fall: Jul 1 to Jul 15
Sow outdoors: May 10 to Jun 7Plant for fall: Jul 15 to Jul 29
Sow outdoors: May 10 to May 31
Sow outdoors: May 17 to Jun 14Plant for fall: Jul 15 to Jul 29
Sow outdoors: May 17 to Jun 7Plant for fall: Jul 29 to Aug 19
Sow outdoors: Jun 7 to Jun 28
Sow outdoors: Jun 7 to Jun 21
Transplant outside: Jun 14 to Jul 5
Plant for fall: Sep 9 to Oct 14
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Aspen, CO
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 8 – Mar 22 | May 3 – May 17 | — | — |
| Peppers | Mar 22 – Apr 5 | Jun 14 – Jun 28 | — | — |
| Eggplant | Mar 22 – Apr 5 | Jun 14 – Jun 28 | — | — |
| Tomatoes | Apr 5 – Apr 19 | Jun 7 – Jun 21 | — | — |
| Lettuce | Apr 5 – Apr 19 | May 10 – May 24 | May 3 – Jun 7 | Jul 29 – Aug 26 |
| Kale | Apr 5 – Apr 19 | May 3 – May 17 | May 3 – May 17 | Jul 15 – Aug 5 |
| Broccoli | Apr 5 – Apr 19 | May 17 – May 31 | — | Jun 17 – Jul 8 |
| Cabbage | Apr 5 – Apr 19 | May 10 – May 24 | — | Jun 17 – Jul 8 |
| Cauliflower | Apr 5 – Apr 19 | May 17 – May 31 | — | Jun 17 – Jul 8 |
| Okra | Apr 19 – May 3 | Jun 21 – Jul 5 | Jun 21 – Jul 5 | — |
| Basil | Apr 19 – May 3 | Jun 7 – Jun 21 | — | — |
| Peas | — | — | Apr 19 – May 10 | Jul 1 – Jul 22 |
| Spinach | — | — | Apr 19 – May 10 | Jul 29 – Aug 19 |
| Radishes | — | — | Apr 26 – Jun 7 | Aug 12 – Sep 2 |
| Cucumbers | May 3 – May 10 | Jun 14 – Jun 21 | Jun 7 – Jun 21 | Jul 8 – Jul 22 |
| Zucchini & Summer Squash | May 3 – May 10 | — | Jun 7 – Jun 21 | Jul 15 – Jul 29 |
| Winter Squash & Pumpkins | May 3 – May 10 | — | Jun 7 – Jun 21 | — |
| Melons & Watermelon | May 3 – May 10 | Jun 14 – Jun 28 | — | — |
| Carrots | — | — | May 10 – Jun 7 | Jul 1 – Jul 15 |
| Beets | — | — | May 10 – Jun 7 | Jul 15 – Jul 29 |
| Potatoes | — | — | May 10 – May 31 | — |
| Swiss Chard | — | — | May 17 – Jun 14 | Jul 15 – Jul 29 |
| Cilantro | — | — | May 17 – Jun 7 | Jul 29 – Aug 19 |
| Green Beans | — | — | Jun 7 – Jun 28 | — |
| Sweet Corn | — | — | Jun 7 – Jun 21 | — |
| Sweet Potatoes | — | Jun 14 – Jul 5 | — | — |
| Garlic | — | — | — | Sep 9 – Oct 14 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Aspen Pitkin Co Ap, CO weather station, about 1 km away (elevation 7,720 ft (2,353 m)).
ZIP codes in Aspen: 81611 81612
Frost dates near Aspen
- Snowmass Village May 31 · Sep 23
- Woody Creek May 31 · Sep 23
- Snowmass May 31 · Sep 23
- Basalt May 31 · Sep 23
- Meredith frost any month
- Carbondale May 31 · Sep 23
- Crested Butte frost any month
- Twin Lakes Jun 16 · Sep 10
Frequently asked questions
When is the last frost in Aspen, CO?
The median last spring frost in Aspen, CO is May 31. There is still about a 10% chance of frost after June 14, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Aspen, CO?
The median first fall frost is September 23, with about a 10% chance of frost before September 11.
How long is the growing season in Aspen, CO?
About 115 days between the median last spring frost and first fall frost.
What planting zone is Aspen, CO?
Aspen, CO is in USDA hardiness zone 5a.