Parker, CO frost dates
Last spring frostMay 9median date
First fall frostOct 3median date
Growing season147 daysfrost-free
Hardiness zone5bZone 5b
How Parker compares
- In 8 years out of 10, the last spring frost in Parker falls between April 27 and May 23, a 26-day window. The first fall frost falls between September 21 and October 15.
- The median last frost is 2 days earlier than the Colorado median of May 11.
- Its 147-day growing season is longer than 52% of the 374 Colorado places with a regular frost season (state median 146 days).
- The last frost is 8 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 177 nights a year at or below 32°F.
- Compared with Castle Rock, CO, 14 km away, the last frost here is the same as there and the growing season is 1 day longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 27 |
| 50% (median) | May 9 |
| 10% (safe for tender plants) | May 23 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 21 |
| 50% (median) | October 3 |
| 90% (late) | October 15 |
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 Parker, CO
Parker, CO frost dates — last frost May 9, first frost Oct 3, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Feb 14 to Feb 28Transplant outside: Apr 11 to Apr 25
Start indoors: Feb 28 to Mar 14Transplant outside: May 23 to Jun 6
Start indoors: Feb 28 to Mar 14Transplant outside: May 23 to Jun 6
Start indoors: Mar 14 to Mar 28Transplant outside: May 16 to May 30
Start indoors: Mar 14 to Mar 28Transplant outside: Apr 18 to May 2Sow outdoors: Apr 11 to May 16Plant for fall: Aug 8 to Sep 5
Start indoors: Mar 14 to Mar 28Transplant outside: Apr 11 to Apr 25Sow outdoors: Apr 11 to Apr 25Plant for fall: Jul 25 to Aug 15
Start indoors: Mar 14 to Mar 28Transplant outside: Apr 25 to May 9Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 14 to Mar 28Transplant outside: Apr 18 to May 2Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 14 to Mar 28Transplant outside: Apr 25 to May 9Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 28 to Apr 11Transplant outside: May 30 to Jun 13Sow outdoors: May 30 to Jun 13
Start indoors: Mar 28 to Apr 11Transplant outside: May 16 to May 30
Sow outdoors: Mar 28 to Apr 18Plant for fall: Jul 11 to Aug 1
Sow outdoors: Mar 28 to Apr 18Plant for fall: Aug 8 to Aug 29
Sow outdoors: Apr 4 to May 16Plant for fall: Aug 22 to Sep 12
Start indoors: Apr 11 to Apr 18Transplant outside: May 23 to May 30Sow outdoors: May 16 to May 30Plant for fall: Jul 18 to Aug 1
Start indoors: Apr 11 to Apr 18Sow outdoors: May 16 to May 30Plant for fall: Jul 25 to Aug 8
Start indoors: Apr 11 to Apr 18Sow outdoors: May 16 to May 30
Start indoors: Apr 11 to Apr 18Transplant outside: May 23 to Jun 6
Sow outdoors: Apr 18 to May 16Plant for fall: Jul 11 to Jul 25
Sow outdoors: Apr 18 to May 16Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 18 to May 9
Sow outdoors: Apr 25 to May 23Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 25 to May 16Plant for fall: Aug 8 to Aug 29
Sow outdoors: May 16 to Jun 6Plant for fall: Jul 18 to Aug 1
Sow outdoors: May 16 to May 30
Transplant outside: May 23 to Jun 13
Plant for fall: Sep 19 to Oct 24
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Parker, CO
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 14 – Feb 28 | Apr 11 – Apr 25 | — | — |
| Peppers | Feb 28 – Mar 14 | May 23 – Jun 6 | — | — |
| Eggplant | Feb 28 – Mar 14 | May 23 – Jun 6 | — | — |
| Tomatoes | Mar 14 – Mar 28 | May 16 – May 30 | — | — |
| Lettuce | Mar 14 – Mar 28 | Apr 18 – May 2 | Apr 11 – May 16 | Aug 8 – Sep 5 |
| Kale | Mar 14 – Mar 28 | Apr 11 – Apr 25 | Apr 11 – Apr 25 | Jul 25 – Aug 15 |
| Broccoli | Mar 14 – Mar 28 | Apr 25 – May 9 | — | Jun 27 – Jul 18 |
| Cabbage | Mar 14 – Mar 28 | Apr 18 – May 2 | — | Jun 27 – Jul 18 |
| Cauliflower | Mar 14 – Mar 28 | Apr 25 – May 9 | — | Jun 27 – Jul 18 |
| Okra | Mar 28 – Apr 11 | May 30 – Jun 13 | May 30 – Jun 13 | — |
| Basil | Mar 28 – Apr 11 | May 16 – May 30 | — | — |
| Peas | — | — | Mar 28 – Apr 18 | Jul 11 – Aug 1 |
| Spinach | — | — | Mar 28 – Apr 18 | Aug 8 – Aug 29 |
| Radishes | — | — | Apr 4 – May 16 | Aug 22 – Sep 12 |
| Cucumbers | Apr 11 – Apr 18 | May 23 – May 30 | May 16 – May 30 | Jul 18 – Aug 1 |
| Zucchini & Summer Squash | Apr 11 – Apr 18 | — | May 16 – May 30 | Jul 25 – Aug 8 |
| Winter Squash & Pumpkins | Apr 11 – Apr 18 | — | May 16 – May 30 | — |
| Melons & Watermelon | Apr 11 – Apr 18 | May 23 – Jun 6 | — | — |
| Carrots | — | — | Apr 18 – May 16 | Jul 11 – Jul 25 |
| Beets | — | — | Apr 18 – May 16 | Jul 25 – Aug 8 |
| Potatoes | — | — | Apr 18 – May 9 | — |
| Swiss Chard | — | — | Apr 25 – May 23 | Jul 25 – Aug 8 |
| Cilantro | — | — | Apr 25 – May 16 | Aug 8 – Aug 29 |
| Green Beans | — | — | May 16 – Jun 6 | Jul 18 – Aug 1 |
| Sweet Corn | — | — | May 16 – May 30 | — |
| Sweet Potatoes | — | May 23 – Jun 13 | — | — |
| Garlic | — | — | — | Sep 19 – Oct 24 |
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 Parker, CO weather station, 3 km away (elevation 5,906 ft (1,800 m)).
ZIP codes in Parker: 80134 80138
Frost dates near Parker
- Lone Tree May 5 · Oct 8
- Castle Rock May 9 · Oct 2
- Franktown May 16 · Oct 2
- Louviers May 16 · Oct 1
- Elizabeth May 16 · Oct 2
- Englewood May 2 · Oct 11
- Littleton May 2 · Oct 11
- Aurora May 7 · Oct 8
- Denver Apr 30 · Oct 12
- Sedalia May 16 · Oct 1
Frequently asked questions
When is the last frost in Parker, CO?
The median last spring frost in Parker, CO is May 9. There is still about a 10% chance of frost after May 23, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Parker, CO?
The median first fall frost is October 3, with about a 10% chance of frost before September 21.
How long is the growing season in Parker, CO?
About 147 days between the median last spring frost and first fall frost.
What planting zone is Parker, CO?
Parker, CO is in USDA hardiness zone 5b.