Green River, WY frost dates
Last spring frostMay 24median date
First fall frostSep 22median date
Growing season121 daysfrost-free
Hardiness zone5aZone 5a
How Green River compares
- In 8 years out of 10, the last spring frost in Green River falls between May 7 and June 10, a 34-day window. The first fall frost falls between September 7 and October 6.
- The median last frost is 3 days later than the Wyoming median of May 21.
- Its 121-day growing season is longer than 38% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 21 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 200 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 7 |
| 50% (median) | May 24 |
| 10% (safe for tender plants) | June 10 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 7 |
| 50% (median) | September 22 |
| 90% (late) | October 6 |
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 Green River, WY
Green River, WY frost dates — last frost May 24, first frost Sep 22, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Mar 1 to Mar 15Transplant outside: Apr 26 to May 10
Start indoors: Mar 15 to Mar 29Transplant outside: Jun 7 to Jun 21
Start indoors: Mar 15 to Mar 29Transplant outside: Jun 7 to Jun 21
Start indoors: Mar 29 to Apr 12Transplant outside: May 31 to Jun 14
Start indoors: Mar 29 to Apr 12Transplant outside: May 3 to May 17Sow outdoors: Apr 26 to May 31Plant for fall: Jul 28 to Aug 25
Start indoors: Mar 29 to Apr 12Transplant outside: Apr 26 to May 10Sow outdoors: Apr 26 to May 10Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 29 to Apr 12Transplant outside: May 10 to May 24Plant for fall: Jun 16 to Jul 7
Start indoors: Mar 29 to Apr 12Transplant outside: May 3 to May 17Plant for fall: Jun 16 to Jul 7
Start indoors: Mar 29 to Apr 12Transplant outside: May 10 to May 24Plant for fall: Jun 16 to Jul 7
Start indoors: Apr 12 to Apr 26Transplant outside: Jun 14 to Jun 28Sow outdoors: Jun 14 to Jun 28
Start indoors: Apr 12 to Apr 26Transplant outside: May 31 to Jun 14
Sow outdoors: Apr 12 to May 3Plant for fall: Jun 30 to Jul 21
Sow outdoors: Apr 12 to May 3Plant for fall: Jul 28 to Aug 18
Sow outdoors: Apr 19 to May 31Plant for fall: Aug 11 to Sep 1
Start indoors: Apr 26 to May 3Transplant outside: Jun 7 to Jun 14Sow outdoors: May 31 to Jun 14Plant for fall: Jul 7 to Jul 21
Start indoors: Apr 26 to May 3Sow outdoors: May 31 to Jun 14Plant for fall: Jul 14 to Jul 28
Start indoors: Apr 26 to May 3Sow outdoors: May 31 to Jun 14
Start indoors: Apr 26 to May 3Transplant outside: Jun 7 to Jun 21
Sow outdoors: May 3 to May 31Plant for fall: Jun 30 to Jul 14
Sow outdoors: May 3 to May 31Plant for fall: Jul 14 to Jul 28
Sow outdoors: May 3 to May 24
Sow outdoors: May 10 to Jun 7Plant for fall: Jul 14 to Jul 28
Sow outdoors: May 10 to May 31Plant for fall: Jul 28 to Aug 18
Sow outdoors: May 31 to Jun 21Plant for fall: Jul 7 to Jul 21
Sow outdoors: May 31 to Jun 14
Transplant outside: Jun 7 to Jun 28
Plant for fall: Sep 8 to Oct 13
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Green River, WY
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 1 – Mar 15 | Apr 26 – May 10 | — | — |
| Peppers | Mar 15 – Mar 29 | Jun 7 – Jun 21 | — | — |
| Eggplant | Mar 15 – Mar 29 | Jun 7 – Jun 21 | — | — |
| Tomatoes | Mar 29 – Apr 12 | May 31 – Jun 14 | — | — |
| Lettuce | Mar 29 – Apr 12 | May 3 – May 17 | Apr 26 – May 31 | Jul 28 – Aug 25 |
| Kale | Mar 29 – Apr 12 | Apr 26 – May 10 | Apr 26 – May 10 | Jul 14 – Aug 4 |
| Broccoli | Mar 29 – Apr 12 | May 10 – May 24 | — | Jun 16 – Jul 7 |
| Cabbage | Mar 29 – Apr 12 | May 3 – May 17 | — | Jun 16 – Jul 7 |
| Cauliflower | Mar 29 – Apr 12 | May 10 – May 24 | — | Jun 16 – Jul 7 |
| Okra | Apr 12 – Apr 26 | Jun 14 – Jun 28 | Jun 14 – Jun 28 | — |
| Basil | Apr 12 – Apr 26 | May 31 – Jun 14 | — | — |
| Peas | — | — | Apr 12 – May 3 | Jun 30 – Jul 21 |
| Spinach | — | — | Apr 12 – May 3 | Jul 28 – Aug 18 |
| Radishes | — | — | Apr 19 – May 31 | Aug 11 – Sep 1 |
| Cucumbers | Apr 26 – May 3 | Jun 7 – Jun 14 | May 31 – Jun 14 | Jul 7 – Jul 21 |
| Zucchini & Summer Squash | Apr 26 – May 3 | — | May 31 – Jun 14 | Jul 14 – Jul 28 |
| Winter Squash & Pumpkins | Apr 26 – May 3 | — | May 31 – Jun 14 | — |
| Melons & Watermelon | Apr 26 – May 3 | Jun 7 – Jun 21 | — | — |
| Carrots | — | — | May 3 – May 31 | Jun 30 – Jul 14 |
| Beets | — | — | May 3 – May 31 | Jul 14 – Jul 28 |
| Potatoes | — | — | May 3 – May 24 | — |
| Swiss Chard | — | — | May 10 – Jun 7 | Jul 14 – Jul 28 |
| Cilantro | — | — | May 10 – May 31 | Jul 28 – Aug 18 |
| Green Beans | — | — | May 31 – Jun 21 | Jul 7 – Jul 21 |
| Sweet Corn | — | — | May 31 – Jun 14 | — |
| Sweet Potatoes | — | Jun 7 – Jun 28 | — | — |
| Garlic | — | — | — | Sep 8 – Oct 13 |
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 Green Rvr, WY weather station, about 1 km away (elevation 6,161 ft (1,878 m)).
Frost dates near Green River
- Rock Springs May 24 · Sep 24
- Reliance May 24 · Sep 24
- Little America May 25 · Sep 27
- Granger May 25 · Sep 27
- Superior May 22 · Sep 28
- Point Of Rocks May 22 · Sep 28
- Farson frost any month
- Mc Kinnon May 22 · Sep 29
- Lyman Jun 14 · Sep 9
- Opal frost any month
Frequently asked questions
When is the last frost in Green River, WY?
The median last spring frost in Green River, WY is May 24. There is still about a 10% chance of frost after June 10, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Green River, WY?
The median first fall frost is September 22, with about a 10% chance of frost before September 7.
How long is the growing season in Green River, WY?
About 121 days between the median last spring frost and first fall frost.
What planting zone is Green River, WY?
Green River, WY is in USDA hardiness zone 5a.