Alton, UT frost dates
Last spring frostJun 1median date
First fall frostSep 30median date
Growing season121 daysfrost-free
Hardiness zone6aZone 6a
How Alton compares
- In 8 years out of 10, the last spring frost in Alton falls between May 16 and June 15, a 30-day window. The first fall frost falls between September 16 and October 12.
- The median last frost is 22 days later than the Utah median of May 10.
- Its 121-day growing season is longer than 20% of the 250 Utah places with a regular frost season (state median 148 days).
- The last frost is 33 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 190 nights a year at or below 32°F.
- Compared with Saint George, UT, 100 km away, the last frost here is 79 days later than there and the growing season is 120 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 16 |
| 50% (median) | June 1 |
| 10% (safe for tender plants) | June 15 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 16 |
| 50% (median) | September 30 |
| 90% (late) | October 12 |
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 Alton, UT
Alton, UT frost dates — last frost Jun 1, first frost Sep 30, zone 6a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 9 to Mar 23Transplant outside: May 4 to May 18
Start indoors: Mar 23 to Apr 6Transplant outside: Jun 15 to Jun 29
Start indoors: Mar 23 to Apr 6Transplant outside: Jun 15 to Jun 29
Start indoors: Apr 6 to Apr 20Transplant outside: Jun 8 to Jun 22
Start indoors: Apr 6 to Apr 20Transplant outside: May 11 to May 25Sow outdoors: May 4 to Jun 8Plant for fall: Aug 5 to Sep 2
Start indoors: Apr 6 to Apr 20Transplant outside: May 4 to May 18Sow outdoors: May 4 to May 18Plant for fall: Jul 22 to Aug 12
Start indoors: Apr 6 to Apr 20Transplant outside: May 18 to Jun 1Plant for fall: Jun 24 to Jul 15
Start indoors: Apr 6 to Apr 20Transplant outside: May 11 to May 25Plant for fall: Jun 24 to Jul 15
Start indoors: Apr 6 to Apr 20Transplant outside: May 18 to Jun 1Plant for fall: Jun 24 to Jul 15
Start indoors: Apr 20 to May 4Transplant outside: Jun 22 to Jul 6Sow outdoors: Jun 22 to Jul 6
Start indoors: Apr 20 to May 4Transplant outside: Jun 8 to Jun 22
Sow outdoors: Apr 20 to May 11Plant for fall: Jul 8 to Jul 29
Sow outdoors: Apr 20 to May 11Plant for fall: Aug 5 to Aug 26
Sow outdoors: Apr 27 to Jun 8Plant for fall: Aug 19 to Sep 9
Start indoors: May 4 to May 11Transplant outside: Jun 15 to Jun 22Sow outdoors: Jun 8 to Jun 22Plant for fall: Jul 15 to Jul 29
Start indoors: May 4 to May 11Sow outdoors: Jun 8 to Jun 22Plant for fall: Jul 22 to Aug 5
Start indoors: May 4 to May 11Sow outdoors: Jun 8 to Jun 22
Start indoors: May 4 to May 11Transplant outside: Jun 15 to Jun 29
Sow outdoors: May 11 to Jun 8Plant for fall: Jul 8 to Jul 22
Sow outdoors: May 11 to Jun 8Plant for fall: Jul 22 to Aug 5
Sow outdoors: May 11 to Jun 1
Sow outdoors: May 18 to Jun 15Plant for fall: Jul 22 to Aug 5
Sow outdoors: May 18 to Jun 8Plant for fall: Aug 5 to Aug 26
Sow outdoors: Jun 8 to Jun 29Plant for fall: Jul 15 to Jul 29
Sow outdoors: Jun 8 to Jun 22
Transplant outside: Jun 15 to Jul 6
Plant for fall: Sep 16 to Oct 21
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Alton, UT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 9 – Mar 23 | May 4 – May 18 | — | — |
| Peppers | Mar 23 – Apr 6 | Jun 15 – Jun 29 | — | — |
| Eggplant | Mar 23 – Apr 6 | Jun 15 – Jun 29 | — | — |
| Tomatoes | Apr 6 – Apr 20 | Jun 8 – Jun 22 | — | — |
| Lettuce | Apr 6 – Apr 20 | May 11 – May 25 | May 4 – Jun 8 | Aug 5 – Sep 2 |
| Kale | Apr 6 – Apr 20 | May 4 – May 18 | May 4 – May 18 | Jul 22 – Aug 12 |
| Broccoli | Apr 6 – Apr 20 | May 18 – Jun 1 | — | Jun 24 – Jul 15 |
| Cabbage | Apr 6 – Apr 20 | May 11 – May 25 | — | Jun 24 – Jul 15 |
| Cauliflower | Apr 6 – Apr 20 | May 18 – Jun 1 | — | Jun 24 – Jul 15 |
| Okra | Apr 20 – May 4 | Jun 22 – Jul 6 | Jun 22 – Jul 6 | — |
| Basil | Apr 20 – May 4 | Jun 8 – Jun 22 | — | — |
| Peas | — | — | Apr 20 – May 11 | Jul 8 – Jul 29 |
| Spinach | — | — | Apr 20 – May 11 | Aug 5 – Aug 26 |
| Radishes | — | — | Apr 27 – Jun 8 | Aug 19 – Sep 9 |
| Cucumbers | May 4 – May 11 | Jun 15 – Jun 22 | Jun 8 – Jun 22 | Jul 15 – Jul 29 |
| Zucchini & Summer Squash | May 4 – May 11 | — | Jun 8 – Jun 22 | Jul 22 – Aug 5 |
| Winter Squash & Pumpkins | May 4 – May 11 | — | Jun 8 – Jun 22 | — |
| Melons & Watermelon | May 4 – May 11 | Jun 15 – Jun 29 | — | — |
| Carrots | — | — | May 11 – Jun 8 | Jul 8 – Jul 22 |
| Beets | — | — | May 11 – Jun 8 | Jul 22 – Aug 5 |
| Potatoes | — | — | May 11 – Jun 1 | — |
| Swiss Chard | — | — | May 18 – Jun 15 | Jul 22 – Aug 5 |
| Cilantro | — | — | May 18 – Jun 8 | Aug 5 – Aug 26 |
| Green Beans | — | — | Jun 8 – Jun 29 | Jul 15 – Jul 29 |
| Sweet Corn | — | — | Jun 8 – Jun 22 | — |
| Sweet Potatoes | — | Jun 15 – Jul 6 | — | — |
| Garlic | — | — | — | Sep 16 – Oct 21 |
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 Alton, UT weather station, 7 km away (elevation 7,100 ft (2,164 m)).
Frost dates near Alton
- Duck Creek Village Jun 1 · Sep 30
- Glendale May 15 · Oct 8
- Hatch Jun 19 · Sep 13
- Orderville May 15 · Oct 8
- Mount Carmel May 15 · Oct 8
- Brian Head Jun 21 · Sep 12
- Bryce May 23 · Sep 27
- Panguitch Jun 12 · Sep 12
- Tropic May 23 · Sep 27
- Cannonville May 31 · Sep 28
Frequently asked questions
When is the last frost in Alton, UT?
The median last spring frost in Alton, UT is June 1. There is still about a 10% chance of frost after June 15, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Alton, UT?
The median first fall frost is September 30, with about a 10% chance of frost before September 16.
How long is the growing season in Alton, UT?
About 121 days between the median last spring frost and first fall frost.
What planting zone is Alton, UT?
Alton, UT is in USDA hardiness zone 6a.