Frost dates for Castleford, 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 17
typical year
Safe to plant
June 5
frost is over in 9 of 10 years
First fall frost
September 29
typical year
Growing season
132 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 19 – May 3 | – |
| Spinach | – | Apr 5 – 26 | Aug 4 – 18 |
| Lettuce | – | Apr 19 – May 10 | Aug 4 – 18 |
| Radishes | – | Apr 19 – May 31 | Aug 18 – Sep 1 |
| Onions | – | Apr 19 – May 3 | – |
| Potatoes | – | Apr 26 – May 10 | – |
| Carrots | – | Apr 26 – May 17 | Jul 7 – 21 |
| Beets | – | Apr 19 – May 3 | Jul 21 – Aug 4 |
| Kale | Mar 8 – 22 | Apr 19 – May 3 | Jul 21 – Aug 4 |
| Broccoli | Mar 8 – 22 | May 3 – 17 | Jul 21 – Aug 4 |
| Cabbage | Feb 22 – Mar 8 | Apr 19 – May 3 | Jul 21 – Aug 4 |
| Garlic | – | – | Aug 18 – Sep 8 |
| Warm-season crops | |||
| Tomatoes | Apr 10 – 24 | Jun 5 – 19 | – |
| Peppers | Apr 3 – 17 | Jun 12 – 26 | – |
| Cucumbers | – | Jun 5 – 26 | – |
| Zucchini | – | Jun 5 – Jul 3 | – |
| Pumpkins | – | Jun 5 – 26 | – |
| Green beans | – | Jun 5 – Jul 21 | – |
| Sweet corn | – | Jun 5 – Jul 3 | – |
| Basil | May 1 – 15 | Jun 12 – 19 | – |
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 5 | May 17 | April 30 |
| Fall frost before | September 11 | September 29 | October 15 |
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 April 30 (May 18 in a late year), and the first one in fall around October 13.
Towns that use these dates
This is the nearest NOAA station with frost records for 1 town.
Castleford
Where these dates come from
NOAA weather station CASTLEFORD 2 N, ID US (USC00101551), 1991–2020 climate normals. It's the nearest station for 2 zip codes, all within 14 miles:
83316, 83321
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.