Frost dates for Arco, 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
May 24
typical year
Safe to plant
June 15
frost is over in 9 of 10 years
First fall frost
October 1
typical year
Growing season
130 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 | – | Apr 26 – May 10 | – |
| Spinach | – | Apr 12 – May 3 | Aug 6 – 20 |
| Lettuce | – | Apr 26 – May 17 | Aug 6 – 20 |
| Radishes | – | Apr 26 – Jun 7 | Aug 20 – Sep 3 |
| Onions | – | Apr 26 – May 10 | – |
| Potatoes | – | May 3 – 17 | – |
| Carrots | – | May 3 – 24 | Jul 9 – 23 |
| Beets | – | Apr 26 – May 10 | Jul 23 – Aug 6 |
| Kale | Mar 15 – 29 | Apr 26 – May 10 | Jul 23 – Aug 6 |
| Broccoli | Mar 15 – 29 | May 10 – 24 | Jul 23 – Aug 6 |
| Cabbage | Mar 1 – 15 | Apr 26 – May 10 | Jul 23 – Aug 6 |
| Garlic | – | – | Aug 20 – Sep 10 |
| Warm-season crops | |||
| Tomatoes | Apr 20 – May 4 | Jun 15 – 29 | – |
| Peppers | Apr 13 – 27 | Jun 22 – Jul 6 | – |
| Cucumbers | – | Jun 15 – Jul 6 | – |
| Zucchini | – | Jun 15 – Jul 13 | – |
| Pumpkins | – | Jun 15 – Jul 6 | – |
| Green beans | – | Jun 15 – Jul 23 | – |
| Sweet corn | – | Jun 15 – Jul 13 | – |
| Basil | May 11 – 25 | Jun 22 – 29 | – |
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 15 | May 24 | May 4 |
| Fall frost before | September 16 | October 1 | October 14 |
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 3 (May 27 in a late year), and the first one in fall around October 13.
Where these dates come from
NOAA weather station ARCO 17 SW, ID US (USW00004126), 1991–2020 climate normals. It's the nearest station for 1 zip code, all within 10 miles:
83213
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.