Koosharem, UT frost dates
Last spring frostJun 6median date
First fall frostSep 21median date
Growing season107 daysfrost-free
Hardiness zone6aZone 6a
How Koosharem compares
- In 8 years out of 10, the last spring frost in Koosharem falls between May 24 and June 26, a 33-day window. The first fall frost falls between September 5 and October 2.
- The median last frost is 27 days later than the Utah median of May 10.
- Its 107-day growing season is longer than 8% of the 250 Utah places with a regular frost season (state median 148 days).
- The last frost is 38 days later than the zone 6a median of Apr 29. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6a chart.
- The weather station records an average of 221 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 24 |
| 50% (median) | June 6 |
| 10% (safe for tender plants) | June 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 5 |
| 50% (median) | September 21 |
| 90% (late) | October 2 |
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 Koosharem, UT
Koosharem, UT frost dates — last frost Jun 6, first frost Sep 21, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Mar 14 to Mar 28Transplant outside: May 9 to May 23
Start indoors: Mar 28 to Apr 11Transplant outside: Jun 20 to Jul 4
Start indoors: Mar 28 to Apr 11Transplant outside: Jun 20 to Jul 4
Start indoors: Apr 11 to Apr 25Transplant outside: Jun 13 to Jun 27
Start indoors: Apr 11 to Apr 25Transplant outside: May 16 to May 30Sow outdoors: May 9 to Jun 13Plant for fall: Jul 27 to Aug 24
Start indoors: Apr 11 to Apr 25Transplant outside: May 9 to May 23Sow outdoors: May 9 to May 23Plant for fall: Jul 13 to Aug 3
Start indoors: Apr 11 to Apr 25Transplant outside: May 23 to Jun 6
Start indoors: Apr 11 to Apr 25Transplant outside: May 16 to May 30
Start indoors: Apr 11 to Apr 25Transplant outside: May 23 to Jun 6
Start indoors: Apr 25 to May 9Transplant outside: Jun 27 to Jul 11Sow outdoors: Jun 27 to Jul 11
Start indoors: Apr 25 to May 9Transplant outside: Jun 13 to Jun 27
Sow outdoors: Apr 25 to May 16Plant for fall: Jun 29 to Jul 20
Sow outdoors: Apr 25 to May 16Plant for fall: Jul 27 to Aug 17
Sow outdoors: May 2 to Jun 13Plant for fall: Aug 10 to Aug 31
Start indoors: May 9 to May 16Transplant outside: Jun 20 to Jun 27Sow outdoors: Jun 13 to Jun 27
Start indoors: May 9 to May 16Sow outdoors: Jun 13 to Jun 27Plant for fall: Jul 13 to Jul 27
Start indoors: May 9 to May 16Sow outdoors: Jun 13 to Jun 27
Start indoors: May 9 to May 16Transplant outside: Jun 20 to Jul 4
Sow outdoors: May 16 to Jun 13Plant for fall: Jun 29 to Jul 13
Sow outdoors: May 16 to Jun 13Plant for fall: Jul 13 to Jul 27
Sow outdoors: May 16 to Jun 6
Sow outdoors: May 23 to Jun 20Plant for fall: Jul 13 to Jul 27
Sow outdoors: May 23 to Jun 13Plant for fall: Jul 27 to Aug 17
Sow outdoors: Jun 13 to Jul 4
Sow outdoors: Jun 13 to Jun 27
Transplant outside: Jun 20 to Jul 11
Plant for fall: Sep 7 to Oct 12
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Koosharem, UT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 14 – Mar 28 | May 9 – May 23 | — | — |
| Peppers | Mar 28 – Apr 11 | Jun 20 – Jul 4 | — | — |
| Eggplant | Mar 28 – Apr 11 | Jun 20 – Jul 4 | — | — |
| Tomatoes | Apr 11 – Apr 25 | Jun 13 – Jun 27 | — | — |
| Lettuce | Apr 11 – Apr 25 | May 16 – May 30 | May 9 – Jun 13 | Jul 27 – Aug 24 |
| Kale | Apr 11 – Apr 25 | May 9 – May 23 | May 9 – May 23 | Jul 13 – Aug 3 |
| Broccoli | Apr 11 – Apr 25 | May 23 – Jun 6 | — | — |
| Cabbage | Apr 11 – Apr 25 | May 16 – May 30 | — | — |
| Cauliflower | Apr 11 – Apr 25 | May 23 – Jun 6 | — | — |
| Okra | Apr 25 – May 9 | Jun 27 – Jul 11 | Jun 27 – Jul 11 | — |
| Basil | Apr 25 – May 9 | Jun 13 – Jun 27 | — | — |
| Peas | — | — | Apr 25 – May 16 | Jun 29 – Jul 20 |
| Spinach | — | — | Apr 25 – May 16 | Jul 27 – Aug 17 |
| Radishes | — | — | May 2 – Jun 13 | Aug 10 – Aug 31 |
| Cucumbers | May 9 – May 16 | Jun 20 – Jun 27 | Jun 13 – Jun 27 | — |
| Zucchini & Summer Squash | May 9 – May 16 | — | Jun 13 – Jun 27 | Jul 13 – Jul 27 |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 107 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 9 – May 16 | — | Jun 13 – Jun 27 | — |
| Melons & Watermelon | May 9 – May 16 | Jun 20 – Jul 4 | — | — |
| Carrots | — | — | May 16 – Jun 13 | Jun 29 – Jul 13 |
| Beets | — | — | May 16 – Jun 13 | Jul 13 – Jul 27 |
| Potatoes | — | — | May 16 – Jun 6 | — |
| Swiss Chard | — | — | May 23 – Jun 20 | Jul 13 – Jul 27 |
| Cilantro | — | — | May 23 – Jun 13 | Jul 27 – Aug 17 |
| Green Beans | — | — | Jun 13 – Jul 4 | — |
| Sweet Corn | — | — | Jun 13 – Jun 27 | — |
| Sweet Potatoes Warning: Your frost-free season is about 107 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 20 – Jul 11 | — | — |
| Garlic | — | — | — | Sep 7 – Oct 12 |
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 Koosharem, UT weather station, about 1 km away (elevation 6,929 ft (2,112 m)).
Frost dates near Koosharem
- Greenwich Jun 6 · Sep 21
- Loa May 31 · Sep 21
- Monroe May 21 · Sep 24
- Annabella May 21 · Sep 24
- Lyman May 31 · Sep 21
- Elsinore May 21 · Sep 24
- Glenwood May 21 · Sep 24
- Richfield May 21 · Sep 24
- Joseph Jun 4 · Sep 21
- Marysvale May 24 · Sep 25
Frequently asked questions
When is the last frost in Koosharem, UT?
The median last spring frost in Koosharem, UT is June 6. There is still about a 10% chance of frost after June 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Koosharem, UT?
The median first fall frost is September 21, with about a 10% chance of frost before September 5.
How long is the growing season in Koosharem, UT?
About 107 days between the median last spring frost and first fall frost.
What planting zone is Koosharem, UT?
Koosharem, UT is in USDA hardiness zone 6a.