Flagler, CO frost dates
Last spring frostMay 5median date
First fall frostOct 8median date
Growing season156 daysfrost-free
Hardiness zone5bZone 5b
How Flagler compares
- In 8 years out of 10, the last spring frost in Flagler falls between April 22 and May 20, a 28-day window. The first fall frost falls between September 27 and October 18.
- The median last frost is 6 days earlier than the Colorado median of May 11.
- Its 156-day growing season is longer than 65% of the 374 Colorado places with a regular frost season (state median 146 days).
- The last frost is 4 days later than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 167 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 22 |
| 50% (median) | May 5 |
| 10% (safe for tender plants) | May 20 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 27 |
| 50% (median) | October 8 |
| 90% (late) | October 18 |
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 Flagler, CO
Flagler, CO frost dates — last frost May 5, first frost Oct 8, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Feb 10 to Feb 24Transplant outside: Apr 7 to Apr 21
Start indoors: Feb 24 to Mar 10Transplant outside: May 19 to Jun 2
Start indoors: Feb 24 to Mar 10Transplant outside: May 19 to Jun 2
Start indoors: Mar 10 to Mar 24Transplant outside: May 12 to May 26
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 14 to Apr 28Sow outdoors: Apr 7 to May 12Plant for fall: Aug 13 to Sep 10
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 7 to Apr 21Sow outdoors: Apr 7 to Apr 21Plant for fall: Jul 30 to Aug 20
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 21 to May 5Plant for fall: Jul 2 to Jul 23
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 14 to Apr 28Plant for fall: Jul 2 to Jul 23
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 21 to May 5Plant for fall: Jul 2 to Jul 23
Start indoors: Mar 24 to Apr 7Transplant outside: May 26 to Jun 9Sow outdoors: May 26 to Jun 9
Start indoors: Mar 24 to Apr 7Transplant outside: May 12 to May 26
Sow outdoors: Mar 24 to Apr 14Plant for fall: Jul 16 to Aug 6
Sow outdoors: Mar 24 to Apr 14Plant for fall: Aug 13 to Sep 3
Sow outdoors: Mar 31 to May 12Plant for fall: Aug 27 to Sep 17
Start indoors: Apr 7 to Apr 14Transplant outside: May 19 to May 26Sow outdoors: May 12 to May 26Plant for fall: Jul 23 to Aug 6
Start indoors: Apr 7 to Apr 14Sow outdoors: May 12 to May 26Plant for fall: Jul 30 to Aug 13
Start indoors: Apr 7 to Apr 14Sow outdoors: May 12 to May 26
Start indoors: Apr 7 to Apr 14Transplant outside: May 19 to Jun 2
Sow outdoors: Apr 14 to May 12Plant for fall: Jul 16 to Jul 30
Sow outdoors: Apr 14 to May 12Plant for fall: Jul 30 to Aug 13
Sow outdoors: Apr 14 to May 5
Sow outdoors: Apr 21 to May 19Plant for fall: Jul 30 to Aug 13
Sow outdoors: Apr 21 to May 12Plant for fall: Aug 13 to Sep 3
Sow outdoors: May 12 to Jun 2Plant for fall: Jul 23 to Aug 6
Sow outdoors: May 12 to May 26
Transplant outside: May 19 to Jun 9
Plant for fall: Sep 24 to Oct 29
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Flagler, CO
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 10 – Feb 24 | Apr 7 – Apr 21 | — | — |
| Peppers | Feb 24 – Mar 10 | May 19 – Jun 2 | — | — |
| Eggplant | Feb 24 – Mar 10 | May 19 – Jun 2 | — | — |
| Tomatoes | Mar 10 – Mar 24 | May 12 – May 26 | — | — |
| Lettuce | Mar 10 – Mar 24 | Apr 14 – Apr 28 | Apr 7 – May 12 | Aug 13 – Sep 10 |
| Kale | Mar 10 – Mar 24 | Apr 7 – Apr 21 | Apr 7 – Apr 21 | Jul 30 – Aug 20 |
| Broccoli | Mar 10 – Mar 24 | Apr 21 – May 5 | — | Jul 2 – Jul 23 |
| Cabbage | Mar 10 – Mar 24 | Apr 14 – Apr 28 | — | Jul 2 – Jul 23 |
| Cauliflower | Mar 10 – Mar 24 | Apr 21 – May 5 | — | Jul 2 – Jul 23 |
| Okra | Mar 24 – Apr 7 | May 26 – Jun 9 | May 26 – Jun 9 | — |
| Basil | Mar 24 – Apr 7 | May 12 – May 26 | — | — |
| Peas | — | — | Mar 24 – Apr 14 | Jul 16 – Aug 6 |
| Spinach | — | — | Mar 24 – Apr 14 | Aug 13 – Sep 3 |
| Radishes | — | — | Mar 31 – May 12 | Aug 27 – Sep 17 |
| Cucumbers | Apr 7 – Apr 14 | May 19 – May 26 | May 12 – May 26 | Jul 23 – Aug 6 |
| Zucchini & Summer Squash | Apr 7 – Apr 14 | — | May 12 – May 26 | Jul 30 – Aug 13 |
| Winter Squash & Pumpkins | Apr 7 – Apr 14 | — | May 12 – May 26 | — |
| Melons & Watermelon | Apr 7 – Apr 14 | May 19 – Jun 2 | — | — |
| Carrots | — | — | Apr 14 – May 12 | Jul 16 – Jul 30 |
| Beets | — | — | Apr 14 – May 12 | Jul 30 – Aug 13 |
| Potatoes | — | — | Apr 14 – May 5 | — |
| Swiss Chard | — | — | Apr 21 – May 19 | Jul 30 – Aug 13 |
| Cilantro | — | — | Apr 21 – May 12 | Aug 13 – Sep 3 |
| Green Beans | — | — | May 12 – Jun 2 | Jul 23 – Aug 6 |
| Sweet Corn | — | — | May 12 – May 26 | — |
| Sweet Potatoes | — | May 19 – Jun 9 | — | — |
| Garlic | — | — | — | Sep 24 – Oct 29 |
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 Flagler 1s, CO weather station, 4 km away (elevation 4,921 ft (1,500 m)).
Frost dates near Flagler
- Seibert May 4 · Oct 11
- Arriba May 5 · Oct 8
- Vona May 4 · Oct 11
- Genoa May 8 · Oct 10
- Stratton May 6 · Oct 9
- Cope May 3 · Oct 9
- Anton May 12 · Oct 4
- Hugo May 10 · Oct 2
- Joes May 3 · Oct 9
- Limon May 21 · Sep 26
Frequently asked questions
When is the last frost in Flagler, CO?
The median last spring frost in Flagler, CO is May 5. There is still about a 10% chance of frost after May 20, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Flagler, CO?
The median first fall frost is October 8, with about a 10% chance of frost before September 27.
How long is the growing season in Flagler, CO?
About 156 days between the median last spring frost and first fall frost.
What planting zone is Flagler, CO?
Flagler, CO is in USDA hardiness zone 5b.