Frost dates for Joliet, MT
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 29
typical year
Safe to plant
June 17
frost is over in 9 of 10 years
First fall frost
September 15
typical year
Growing season
107 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 1 – 15 | – |
| Spinach | – | Apr 17 – May 8 | Jul 21 – Aug 4 |
| Lettuce | – | May 1 – 22 | Jul 21 – Aug 4 |
| Radishes | – | May 1 – Jun 12 | Aug 4 – 18 |
| Onions | – | May 1 – 15 | – |
| Potatoes | – | May 8 – 22 | – |
| Carrots | – | May 8 – 29 | Jun 23 – Jul 7 |
| Beets | – | May 1 – 15 | Jul 7 – 21 |
| Kale | Mar 20 – Apr 3 | May 1 – 15 | Jul 7 – 21 |
| Broccoli | Mar 20 – Apr 3 | May 15 – 29 | Jul 7 – 21 |
| Cabbage | Mar 6 – 20 | May 1 – 15 | Jul 7 – 21 |
| Garlic | – | – | Aug 4 – 25 |
| Warm-season crops | |||
| Tomatoes | Apr 22 – May 6 | Jun 17 – Jul 1 | – |
| Peppers | Apr 15 – 29 | Jun 24 – Jul 8 | – |
| Cucumbers | – | Jun 17 – Jul 8 | – |
| Zucchini | – | Jun 17 – Jul 15 | – |
| Pumpkins | Season usually too short. Try a quick variety or row covers. | ||
| Green beans | – | Jun 17 – Jul 7 | – |
| Sweet corn | – | Jun 17 – Jul 15 | – |
| Basil | May 13 – 27 | Jun 24 – Jul 1 | – |
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 17 | May 29 | May 14 |
| Fall frost before | September 1 | September 15 | October 1 |
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 13 (May 31 in a late year), and the first one in fall around September 26.
Towns that use these dates
This is the nearest NOAA station with frost records for 1 town.
Joliet
Where these dates come from
NOAA weather station JOLIET, MT US (USC00244506), 1991–2020 climate normals. It's the nearest station for 5 zip codes, all within 13 miles:
59013, 59026, 59041, 59063, 59070
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.