Frost dates for Idaho Falls, ID
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
June 9
typical year
Safe to plant
June 26
frost is over in 9 of 10 years
First fall frost
September 11
typical year
Growing season
93 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | May 12 – 26 | – |
| Spinach | – | Apr 28 – May 19 | Jul 17 – 31 |
| Lettuce | – | May 12 – Jun 2 | Jul 17 – 31 |
| Radishes | – | May 12 – Jun 23 | Jul 31 – Aug 14 |
| Onions | – | May 12 – 26 | – |
| Potatoes | Season usually too short. Try a quick variety or row covers. | ||
| Carrots | – | May 19 – Jun 9 | Jun 19 – Jul 3 |
| Beets | – | May 12 – 26 | Jul 3 – 17 |
| Kale | Mar 31 – Apr 14 | May 12 – 26 | Jul 3 – 17 |
| Broccoli | Mar 31 – Apr 14 | May 26 – Jun 9 | Jul 3 – 17 |
| Cabbage | Mar 17 – 31 | May 12 – 26 | Jul 3 – 17 |
| Garlic | – | – | Jul 31 – Aug 21 |
| Warm-season crops | |||
| Tomatoes | May 1 – 15 | Jun 26 – Jul 10 | – |
| Peppers | Season usually too short. Try a quick variety or row covers. | ||
| Cucumbers | – | Jun 26 – Jul 17 | – |
| Zucchini | – | Jun 26 – Jul 24 | – |
| Pumpkins | Season usually too short. Try a quick variety or row covers. | ||
| Green beans | – | Jun 26 – Jul 3 | – |
| Sweet corn | Season usually too short. Try a quick variety or row covers. | ||
| Basil | May 22 – Jun 5 | Jul 3 – 10 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | June 26 | June 9 | May 19 |
| Fall frost before | August 27 | September 11 | September 27 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around May 19 (June 10 in a late year), and the first one in fall around September 23.
Where these dates come from
NOAA weather station IDAHO FALLS 16 SE, ID US (USC00104456), 1991–2020 climate normals. It's the nearest station for 4 zip codes, all within 22 miles:
83236, 83427, 83443, 83449
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.