Polson, MT frost dates
Last spring frostMay 10median date
First fall frostOct 5median date
Growing season148 daysfrost-free
Hardiness zone6aZone 6a
How Polson compares
- In 8 years out of 10, the last spring frost in Polson falls between April 27 and May 26, a 29-day window. The first fall frost falls between September 22 and October 19.
- The median last frost is 9 days earlier than the Montana median of May 19.
- Its 148-day growing season is longer than 92% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 11 days later than the zone 6a median of Apr 29. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6a chart.
- The weather station records an average of 147 nights a year at or below 32°F.
- Compared with Missoula, MT, 90 km away, the last frost here is the same as there and the growing season is 4 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 27 |
| 50% (median) | May 10 |
| 10% (safe for tender plants) | May 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 22 |
| 50% (median) | October 5 |
| 90% (late) | October 19 |
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 Polson, MT
Polson, MT frost dates — last frost May 10, first frost Oct 5, zone 6a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 15 to Mar 1Transplant outside: Apr 12 to Apr 26
Start indoors: Mar 1 to Mar 15Transplant outside: May 24 to Jun 7
Start indoors: Mar 1 to Mar 15Transplant outside: May 24 to Jun 7
Start indoors: Mar 15 to Mar 29Transplant outside: May 17 to May 31
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 19 to May 3Sow outdoors: Apr 12 to May 17Plant for fall: Aug 10 to Sep 7
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 12 to Apr 26Sow outdoors: Apr 12 to Apr 26Plant for fall: Jul 27 to Aug 17
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 26 to May 10Plant for fall: Jun 29 to Jul 20
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 19 to May 3Plant for fall: Jun 29 to Jul 20
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 26 to May 10Plant for fall: Jun 29 to Jul 20
Start indoors: Mar 29 to Apr 12Transplant outside: May 31 to Jun 14Sow outdoors: May 31 to Jun 14
Start indoors: Mar 29 to Apr 12Transplant outside: May 17 to May 31
Sow outdoors: Mar 29 to Apr 19Plant for fall: Jul 13 to Aug 3
Sow outdoors: Mar 29 to Apr 19Plant for fall: Aug 10 to Aug 31
Sow outdoors: Apr 5 to May 17Plant for fall: Aug 24 to Sep 14
Start indoors: Apr 12 to Apr 19Transplant outside: May 24 to May 31Sow outdoors: May 17 to May 31Plant for fall: Jul 20 to Aug 3
Start indoors: Apr 12 to Apr 19Sow outdoors: May 17 to May 31Plant for fall: Jul 27 to Aug 10
Start indoors: Apr 12 to Apr 19Sow outdoors: May 17 to May 31
Start indoors: Apr 12 to Apr 19Transplant outside: May 24 to Jun 7
Sow outdoors: Apr 19 to May 17Plant for fall: Jul 13 to Jul 27
Sow outdoors: Apr 19 to May 17Plant for fall: Jul 27 to Aug 10
Sow outdoors: Apr 19 to May 10
Sow outdoors: Apr 26 to May 24Plant for fall: Jul 27 to Aug 10
Sow outdoors: Apr 26 to May 17Plant for fall: Aug 10 to Aug 31
Sow outdoors: May 17 to Jun 7Plant for fall: Jul 20 to Aug 3
Sow outdoors: May 17 to May 31
Transplant outside: May 24 to Jun 14
Plant for fall: Sep 21 to Oct 26
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Polson, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 15 – Mar 1 | Apr 12 – Apr 26 | — | — |
| Peppers | Mar 1 – Mar 15 | May 24 – Jun 7 | — | — |
| Eggplant | Mar 1 – Mar 15 | May 24 – Jun 7 | — | — |
| Tomatoes | Mar 15 – Mar 29 | May 17 – May 31 | — | — |
| Lettuce | Mar 15 – Mar 29 | Apr 19 – May 3 | Apr 12 – May 17 | Aug 10 – Sep 7 |
| Kale | Mar 15 – Mar 29 | Apr 12 – Apr 26 | Apr 12 – Apr 26 | Jul 27 – Aug 17 |
| Broccoli | Mar 15 – Mar 29 | Apr 26 – May 10 | — | Jun 29 – Jul 20 |
| Cabbage | Mar 15 – Mar 29 | Apr 19 – May 3 | — | Jun 29 – Jul 20 |
| Cauliflower | Mar 15 – Mar 29 | Apr 26 – May 10 | — | Jun 29 – Jul 20 |
| Okra | Mar 29 – Apr 12 | May 31 – Jun 14 | May 31 – Jun 14 | — |
| Basil | Mar 29 – Apr 12 | May 17 – May 31 | — | — |
| Peas | — | — | Mar 29 – Apr 19 | Jul 13 – Aug 3 |
| Spinach | — | — | Mar 29 – Apr 19 | Aug 10 – Aug 31 |
| Radishes | — | — | Apr 5 – May 17 | Aug 24 – Sep 14 |
| Cucumbers | Apr 12 – Apr 19 | May 24 – May 31 | May 17 – May 31 | Jul 20 – Aug 3 |
| Zucchini & Summer Squash | Apr 12 – Apr 19 | — | May 17 – May 31 | Jul 27 – Aug 10 |
| Winter Squash & Pumpkins | Apr 12 – Apr 19 | — | May 17 – May 31 | — |
| Melons & Watermelon | Apr 12 – Apr 19 | May 24 – Jun 7 | — | — |
| Carrots | — | — | Apr 19 – May 17 | Jul 13 – Jul 27 |
| Beets | — | — | Apr 19 – May 17 | Jul 27 – Aug 10 |
| Potatoes | — | — | Apr 19 – May 10 | — |
| Swiss Chard | — | — | Apr 26 – May 24 | Jul 27 – Aug 10 |
| Cilantro | — | — | Apr 26 – May 17 | Aug 10 – Aug 31 |
| Green Beans | — | — | May 17 – Jun 7 | Jul 20 – Aug 3 |
| Sweet Corn | — | — | May 17 – May 31 | — |
| Sweet Potatoes | — | May 24 – Jun 14 | — | — |
| Garlic | — | — | — | Sep 21 – Oct 26 |
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 Polson, MT weather station, 4 km away (elevation 3,009 ft (917 m)).
Frost dates near Polson
- Pablo May 10 · Oct 5
- Ronan May 10 · Oct 5
- Big Arm May 15 · Sep 28
- Dayton May 1 · Oct 15
- Elmo May 15 · Sep 28
- Rollins May 1 · Oct 15
- Charlo May 12 · Oct 2
- Proctor May 1 · Oct 15
- Lakeside May 12 · Sep 25
- Condon May 20 · Sep 22
Frequently asked questions
When is the last frost in Polson, MT?
The median last spring frost in Polson, MT is May 10. There is still about a 10% chance of frost after May 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Polson, MT?
The median first fall frost is October 5, with about a 10% chance of frost before September 22.
How long is the growing season in Polson, MT?
About 148 days between the median last spring frost and first fall frost.
What planting zone is Polson, MT?
Polson, MT is in USDA hardiness zone 6a.