Frost Report

All states Montana

Frost dates for Joplin, 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 21

typical year

Safe to plant

June 6

frost is over in 9 of 10 years

First fall frost

September 19

typical year

Growing season

119 days

frost-free, typical year

When to plant

Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.

CropStart indoorsPlant outsideFall planting
Cool-season crops
Peas – Apr 23 – May 7 –
Spinach – Apr 9 – 30 Jul 25 – Aug 8
Lettuce – Apr 23 – May 14 Jul 25 – Aug 8
Radishes – Apr 23 – Jun 4 Aug 8 – 22
Onions – Apr 23 – May 7 –
Potatoes – Apr 30 – May 14 –
Carrots – Apr 30 – May 21 Jun 27 – Jul 11
Beets – Apr 23 – May 7 Jul 11 – 25
Kale Mar 12 – 26 Apr 23 – May 7 Jul 11 – 25
Broccoli Mar 12 – 26 May 7 – 21 Jul 11 – 25
Cabbage Feb 26 – Mar 12 Apr 23 – May 7 Jul 11 – 25
Garlic – – Aug 8 – 29
Warm-season crops
Tomatoes Apr 11 – 25 Jun 6 – 20 –
Peppers Apr 4 – 18 Jun 13 – 27 –
Cucumbers – Jun 6 – 27 –
Zucchini – Jun 6 – Jul 4 –
Pumpkins – Jun 6 – 27 –
Green beans – Jun 6 – Jul 11 –
Sweet corn – Jun 6 – Jul 4 –
Basil May 2 – 16 Jun 13 – 20 –

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 10Half of years9 years in 10
Spring frost after June 6May 21May 8
Fall frost before September 3September 19October 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 7 (May 23 in a late year), and the first one in fall around September 29.

Where these dates come from

NOAA weather station JOPLIN, MT US (USC00244512), 1991–2020 climate normals. It's the nearest station for 2 zip codes, all within 10 miles:

59530, 59540

Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.