Alma, CO frost dates
Last spring frostJun 16median date
First fall frostSep 9median date
Growing season85 daysfrost-free
Hardiness zone5aZone 5a
How Alma compares
- In 8 years out of 10, the last spring frost in Alma falls between June 2 and June 30, a 28-day window. The first fall frost falls between August 21 and September 24.
- The median last frost is 36 days later than the Colorado median of May 11.
- Its 85-day growing season is longer than 5% of the 374 Colorado places with a regular frost season (state median 146 days).
- The last frost is 44 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 236 nights a year at or below 32°F.
- Compared with Arvada, CO, 101 km away, the last frost here is 42 days later than there and the growing season is 68 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | June 2 |
| 50% (median) | June 16 |
| 10% (safe for tender plants) | June 30 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 21 |
| 50% (median) | September 9 |
| 90% (late) | September 24 |
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 Alma, CO
Alma, CO frost dates — last frost Jun 16, first frost Sep 9, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Mar 24 to Apr 7Transplant outside: May 19 to Jun 2
Start indoors: Apr 7 to Apr 21Transplant outside: Jun 30 to Jul 14
Start indoors: Apr 7 to Apr 21Transplant outside: Jun 30 to Jul 14
Start indoors: Apr 21 to May 5Transplant outside: Jun 23 to Jul 7
Start indoors: Apr 21 to May 5Transplant outside: May 26 to Jun 9Sow outdoors: May 19 to Jun 23Plant for fall: Jul 15 to Aug 12
Start indoors: Apr 21 to May 5Transplant outside: May 19 to Jun 2Sow outdoors: May 19 to Jun 2Plant for fall: Jul 1 to Jul 22
Start indoors: Apr 21 to May 5Transplant outside: Jun 2 to Jun 16
Start indoors: Apr 21 to May 5Transplant outside: May 26 to Jun 9
Start indoors: Apr 21 to May 5Transplant outside: Jun 2 to Jun 16
Start indoors: May 5 to May 19Transplant outside: Jul 7 to Jul 21Sow outdoors: Jul 7 to Jul 21
Start indoors: May 5 to May 19Transplant outside: Jun 23 to Jul 7
Sow outdoors: May 5 to May 26
Sow outdoors: May 5 to May 26Plant for fall: Jul 15 to Aug 5
Sow outdoors: May 12 to Jun 23Plant for fall: Jul 29 to Aug 19
Start indoors: May 19 to May 26Transplant outside: Jun 30 to Jul 7Sow outdoors: Jun 23 to Jul 7
Start indoors: May 19 to May 26Sow outdoors: Jun 23 to Jul 7
Start indoors: May 19 to May 26Sow outdoors: Jun 23 to Jul 7
Start indoors: May 19 to May 26Transplant outside: Jun 30 to Jul 14
Sow outdoors: May 26 to Jun 23
Sow outdoors: May 26 to Jun 23
Sow outdoors: May 26 to Jun 16
Sow outdoors: Jun 2 to Jun 30
Sow outdoors: Jun 2 to Jun 23Plant for fall: Jul 15 to Aug 5
Sow outdoors: Jun 23 to Jul 14
Sow outdoors: Jun 23 to Jul 7
Transplant outside: Jun 30 to Jul 21
Plant for fall: Aug 26 to Sep 30
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Alma, CO
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 24 – Apr 7 | May 19 – Jun 2 | — | — |
| Peppers Warning: Your frost-free season is about 85 days, which is tight for peppers (75+ days). Choose early varieties and use transplants or row covers. | Apr 7 – Apr 21 | Jun 30 – Jul 14 | — | — |
| Eggplant Warning: Your frost-free season is about 85 days, which is tight for eggplant (75+ days). Choose early varieties and use transplants or row covers. | Apr 7 – Apr 21 | Jun 30 – Jul 14 | — | — |
| Tomatoes | Apr 21 – May 5 | Jun 23 – Jul 7 | — | — |
| Lettuce | Apr 21 – May 5 | May 26 – Jun 9 | May 19 – Jun 23 | Jul 15 – Aug 12 |
| Kale | Apr 21 – May 5 | May 19 – Jun 2 | May 19 – Jun 2 | Jul 1 – Jul 22 |
| Broccoli | Apr 21 – May 5 | Jun 2 – Jun 16 | — | — |
| Cabbage | Apr 21 – May 5 | May 26 – Jun 9 | — | — |
| Cauliflower | Apr 21 – May 5 | Jun 2 – Jun 16 | — | — |
| Okra | May 5 – May 19 | Jul 7 – Jul 21 | Jul 7 – Jul 21 | — |
| Basil | May 5 – May 19 | Jun 23 – Jul 7 | — | — |
| Peas | — | — | May 5 – May 26 | — |
| Spinach | — | — | May 5 – May 26 | Jul 15 – Aug 5 |
| Radishes | — | — | May 12 – Jun 23 | Jul 29 – Aug 19 |
| Cucumbers | May 19 – May 26 | Jun 30 – Jul 7 | Jun 23 – Jul 7 | — |
| Zucchini & Summer Squash | May 19 – May 26 | — | Jun 23 – Jul 7 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 85 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 19 – May 26 | — | Jun 23 – Jul 7 | — |
| Melons & Watermelon Warning: Your frost-free season is about 85 days, which is tight for melons & watermelon (85+ days). Choose early varieties and use transplants or row covers. | May 19 – May 26 | Jun 30 – Jul 14 | — | — |
| Carrots | — | — | May 26 – Jun 23 | — |
| Beets | — | — | May 26 – Jun 23 | — |
| Potatoes | — | — | May 26 – Jun 16 | — |
| Swiss Chard | — | — | Jun 2 – Jun 30 | — |
| Cilantro | — | — | Jun 2 – Jun 23 | Jul 15 – Aug 5 |
| Green Beans | — | — | Jun 23 – Jul 14 | — |
| Sweet Corn Warning: Your frost-free season is about 85 days, which is tight for sweet corn (80+ days). Choose early varieties and use transplants or row covers. | — | — | Jun 23 – Jul 7 | — |
| Sweet Potatoes Warning: Your frost-free season is about 85 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 30 – Jul 21 | — | — |
| Garlic | — | — | — | Aug 26 – Sep 30 |
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 Fairplay S Park Rd, CO weather station, 9 km away (elevation 9,997 ft (3,047 m)).
Frost dates near Alma
- Fairplay Jun 16 · Sep 9
- Leadville frost any month
- Breckenridge frost any month
- Climax frost any month
- Como Jun 16 · Sep 9
- Frisco frost any month
- Jefferson Jun 15 · Sep 9
- Granite Jun 16 · Sep 10
- Dillon frost any month
- Red Cliff Jun 21 · Sep 7
Frequently asked questions
When is the last frost in Alma, CO?
The median last spring frost in Alma, CO is June 16. There is still about a 10% chance of frost after June 30, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Alma, CO?
The median first fall frost is September 9, with about a 10% chance of frost before August 21.
How long is the growing season in Alma, CO?
About 85 days between the median last spring frost and first fall frost.
What planting zone is Alma, CO?
Alma, CO is in USDA hardiness zone 5a.