Shawmut, MT frost dates
Last spring frostMay 23median date
First fall frostSep 16median date
Growing season116 daysfrost-free
Hardiness zone4bZone 4b
How Shawmut compares
- In 8 years out of 10, the last spring frost in Shawmut falls between May 12 and June 6, a 25-day window. The first fall frost falls between September 1 and September 28.
- The median last frost is 4 days later than the Montana median of May 19.
- Its 116-day growing season is longer than 30% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 15 days later than the zone 4b median of May 8. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4b chart.
- The weather station records an average of 191 nights a year at or below 32°F.
- Compared with Billings, MT, 106 km away, the last frost here is 19 days later than there and the growing season is 40 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 12 |
| 50% (median) | May 23 |
| 10% (safe for tender plants) | June 6 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 1 |
| 50% (median) | September 16 |
| 90% (late) | September 28 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Shawmut, MT
Shawmut, MT frost dates — last frost May 23, first frost Sep 16, zone 4b. whenisthelastfrost.com
Crop
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Start indoors: Feb 28 to Mar 14Transplant outside: Apr 25 to May 9
Start indoors: Mar 14 to Mar 28Transplant outside: Jun 6 to Jun 20
Start indoors: Mar 14 to Mar 28Transplant outside: Jun 6 to Jun 20
Start indoors: Mar 28 to Apr 11Transplant outside: May 30 to Jun 13
Start indoors: Mar 28 to Apr 11Transplant outside: May 2 to May 16Sow outdoors: Apr 25 to May 30Plant for fall: Jul 22 to Aug 19
Start indoors: Mar 28 to Apr 11Transplant outside: Apr 25 to May 9Sow outdoors: Apr 25 to May 9Plant for fall: Jul 8 to Jul 29
Start indoors: Mar 28 to Apr 11Transplant outside: May 9 to May 23Plant for fall: Jun 10 to Jul 1
Start indoors: Mar 28 to Apr 11Transplant outside: May 2 to May 16Plant for fall: Jun 10 to Jul 1
Start indoors: Mar 28 to Apr 11Transplant outside: May 9 to May 23Plant for fall: Jun 10 to Jul 1
Start indoors: Apr 11 to Apr 25Transplant outside: Jun 13 to Jun 27Sow outdoors: Jun 13 to Jun 27
Start indoors: Apr 11 to Apr 25Transplant outside: May 30 to Jun 13
Sow outdoors: Apr 11 to May 2Plant for fall: Jun 24 to Jul 15
Sow outdoors: Apr 11 to May 2Plant for fall: Jul 22 to Aug 12
Sow outdoors: Apr 18 to May 30Plant for fall: Aug 5 to Aug 26
Start indoors: Apr 25 to May 2Transplant outside: Jun 6 to Jun 13Sow outdoors: May 30 to Jun 13Plant for fall: Jul 1 to Jul 15
Start indoors: Apr 25 to May 2Sow outdoors: May 30 to Jun 13Plant for fall: Jul 8 to Jul 22
Start indoors: Apr 25 to May 2Sow outdoors: May 30 to Jun 13
Start indoors: Apr 25 to May 2Transplant outside: Jun 6 to Jun 20
Sow outdoors: May 2 to May 30Plant for fall: Jun 24 to Jul 8
Sow outdoors: May 2 to May 30Plant for fall: Jul 8 to Jul 22
Sow outdoors: May 2 to May 23
Sow outdoors: May 9 to Jun 6Plant for fall: Jul 8 to Jul 22
Sow outdoors: May 9 to May 30Plant for fall: Jul 22 to Aug 12
Sow outdoors: May 30 to Jun 20
Sow outdoors: May 30 to Jun 13
Transplant outside: Jun 6 to Jun 27
Plant for fall: Sep 2 to Oct 7
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Shawmut, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 28 – Mar 14 | Apr 25 – May 9 | — | — |
| Peppers | Mar 14 – Mar 28 | Jun 6 – Jun 20 | — | — |
| Eggplant | Mar 14 – Mar 28 | Jun 6 – Jun 20 | — | — |
| Tomatoes | Mar 28 – Apr 11 | May 30 – Jun 13 | — | — |
| Lettuce | Mar 28 – Apr 11 | May 2 – May 16 | Apr 25 – May 30 | Jul 22 – Aug 19 |
| Kale | Mar 28 – Apr 11 | Apr 25 – May 9 | Apr 25 – May 9 | Jul 8 – Jul 29 |
| Broccoli | Mar 28 – Apr 11 | May 9 – May 23 | — | Jun 10 – Jul 1 |
| Cabbage | Mar 28 – Apr 11 | May 2 – May 16 | — | Jun 10 – Jul 1 |
| Cauliflower | Mar 28 – Apr 11 | May 9 – May 23 | — | Jun 10 – Jul 1 |
| Okra | Apr 11 – Apr 25 | Jun 13 – Jun 27 | Jun 13 – Jun 27 | — |
| Basil | Apr 11 – Apr 25 | May 30 – Jun 13 | — | — |
| Peas | — | — | Apr 11 – May 2 | Jun 24 – Jul 15 |
| Spinach | — | — | Apr 11 – May 2 | Jul 22 – Aug 12 |
| Radishes | — | — | Apr 18 – May 30 | Aug 5 – Aug 26 |
| Cucumbers | Apr 25 – May 2 | Jun 6 – Jun 13 | May 30 – Jun 13 | Jul 1 – Jul 15 |
| Zucchini & Summer Squash | Apr 25 – May 2 | — | May 30 – Jun 13 | Jul 8 – Jul 22 |
| Winter Squash & Pumpkins | Apr 25 – May 2 | — | May 30 – Jun 13 | — |
| Melons & Watermelon | Apr 25 – May 2 | Jun 6 – Jun 20 | — | — |
| Carrots | — | — | May 2 – May 30 | Jun 24 – Jul 8 |
| Beets | — | — | May 2 – May 30 | Jul 8 – Jul 22 |
| Potatoes | — | — | May 2 – May 23 | — |
| Swiss Chard | — | — | May 9 – Jun 6 | Jul 8 – Jul 22 |
| Cilantro | — | — | May 9 – May 30 | Jul 22 – Aug 12 |
| Green Beans | — | — | May 30 – Jun 20 | — |
| Sweet Corn | — | — | May 30 – Jun 13 | — |
| Sweet Potatoes | — | Jun 6 – Jun 27 | — | — |
| Garlic | — | — | — | Sep 2 – Oct 7 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Harlowton, MT weather station, 20 km away (elevation 4,222 ft (1,287 m)).
Frost dates near Shawmut
- Harlowton May 23 · Sep 16
- Ryegate May 17 · Sep 23
- Judith Gap Jun 1 · Sep 15
- Melville Jun 9 · Sep 7
- Two Dot May 23 · Sep 16
- Lavina May 22 · Sep 15
- Buffalo Jun 1 · Sep 15
- Rapelje May 24 · Sep 21
- Martinsdale Jun 3 · Sep 8
- Moore May 23 · Sep 21
Frequently asked questions
When is the last frost in Shawmut, MT?
The median last spring frost in Shawmut, MT is May 23. There is still about a 10% chance of frost after June 6, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Shawmut, MT?
The median first fall frost is September 16, with about a 10% chance of frost before September 1.
How long is the growing season in Shawmut, MT?
About 116 days between the median last spring frost and first fall frost.
What planting zone is Shawmut, MT?
Shawmut, MT is in USDA hardiness zone 4b.