Frost dates for Mizpah, 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 22
typical year
Safe to plant
June 7
frost is over in 9 of 10 years
First fall frost
September 15
typical year
Growing season
117 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 24 – May 8 | – |
| Spinach | – | Apr 10 – May 1 | Jul 21 – Aug 4 |
| Lettuce | – | Apr 24 – May 15 | Jul 21 – Aug 4 |
| Radishes | – | Apr 24 – Jun 5 | Aug 4 – 18 |
| Onions | – | Apr 24 – May 8 | – |
| Potatoes | – | May 1 – 15 | – |
| Carrots | – | May 1 – 22 | Jun 23 – Jul 7 |
| Beets | – | Apr 24 – May 8 | Jul 7 – 21 |
| Kale | Mar 13 – 27 | Apr 24 – May 8 | Jul 7 – 21 |
| Broccoli | Mar 13 – 27 | May 8 – 22 | Jul 7 – 21 |
| Cabbage | Feb 27 – Mar 13 | Apr 24 – May 8 | Jul 7 – 21 |
| Garlic | – | – | Aug 4 – 25 |
| Warm-season crops | |||
| Tomatoes | Apr 12 – 26 | Jun 7 – 21 | – |
| Peppers | Apr 5 – 19 | Jun 14 – 28 | – |
| Cucumbers | – | Jun 7 – 28 | – |
| Zucchini | – | Jun 7 – Jul 5 | – |
| Pumpkins | – | Jun 7 – 28 | – |
| Green beans | – | Jun 7 – Jul 7 | – |
| Sweet corn | – | Jun 7 – Jul 5 | – |
| Basil | May 3 – 17 | Jun 14 – 21 | – |
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 7 | May 22 | May 9 |
| Fall frost before | September 2 | 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 11 (May 28 in a late year), and the first one in fall around September 25.
Where these dates come from
NOAA weather station MIZPAH 4 NNW, MT US (USC00245754), 1991–2020 climate normals. It's the nearest station for 1 zip code, all within 17 miles:
59336
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.