Roscoe, MT frost dates
Last spring frostJun 5median date
First fall frostSep 14median date
Growing season101 daysfrost-free
Hardiness zone5aZone 5a
How Roscoe compares
- In 8 years out of 10, the last spring frost in Roscoe falls between May 22 and June 21, a 30-day window. The first fall frost falls between August 31 and September 28.
- The median last frost is 17 days later than the Montana median of May 19.
- Its 101-day growing season is longer than 12% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 33 days later than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 178 nights a year at or below 32°F.
- Compared with Billings, MT, 101 km away, the last frost here is 32 days later than there and the growing season is 55 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 22 |
| 50% (median) | June 5 |
| 10% (safe for tender plants) | June 21 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 31 |
| 50% (median) | September 14 |
| 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 Roscoe, MT
Roscoe, MT frost dates — last frost Jun 5, first frost Sep 14, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 13 to Mar 27Transplant outside: May 8 to May 22
Start indoors: Mar 27 to Apr 10Transplant outside: Jun 19 to Jul 3
Start indoors: Mar 27 to Apr 10Transplant outside: Jun 19 to Jul 3
Start indoors: Apr 10 to Apr 24Transplant outside: Jun 12 to Jun 26
Start indoors: Apr 10 to Apr 24Transplant outside: May 15 to May 29Sow outdoors: May 8 to Jun 12Plant for fall: Jul 20 to Aug 17
Start indoors: Apr 10 to Apr 24Transplant outside: May 8 to May 22Sow outdoors: May 8 to May 22Plant for fall: Jul 6 to Jul 27
Start indoors: Apr 10 to Apr 24Transplant outside: May 22 to Jun 5
Start indoors: Apr 10 to Apr 24Transplant outside: May 15 to May 29
Start indoors: Apr 10 to Apr 24Transplant outside: May 22 to Jun 5
Start indoors: Apr 24 to May 8Transplant outside: Jun 26 to Jul 10Sow outdoors: Jun 26 to Jul 10
Start indoors: Apr 24 to May 8Transplant outside: Jun 12 to Jun 26
Sow outdoors: Apr 24 to May 15Plant for fall: Jun 22 to Jul 13
Sow outdoors: Apr 24 to May 15Plant for fall: Jul 20 to Aug 10
Sow outdoors: May 1 to Jun 12Plant for fall: Aug 3 to Aug 24
Start indoors: May 8 to May 15Transplant outside: Jun 19 to Jun 26Sow outdoors: Jun 12 to Jun 26
Start indoors: May 8 to May 15Sow outdoors: Jun 12 to Jun 26
Start indoors: May 8 to May 15Sow outdoors: Jun 12 to Jun 26
Start indoors: May 8 to May 15Transplant outside: Jun 19 to Jul 3
Sow outdoors: May 15 to Jun 12
Sow outdoors: May 15 to Jun 12Plant for fall: Jul 6 to Jul 20
Sow outdoors: May 15 to Jun 5
Sow outdoors: May 22 to Jun 19Plant for fall: Jul 6 to Jul 20
Sow outdoors: May 22 to Jun 12Plant for fall: Jul 20 to Aug 10
Sow outdoors: Jun 12 to Jul 3
Sow outdoors: Jun 12 to Jun 26
Transplant outside: Jun 19 to Jul 10
Plant for fall: Aug 31 to Oct 5
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Roscoe, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 13 – Mar 27 | May 8 – May 22 | — | — |
| Peppers | Mar 27 – Apr 10 | Jun 19 – Jul 3 | — | — |
| Eggplant | Mar 27 – Apr 10 | Jun 19 – Jul 3 | — | — |
| Tomatoes | Apr 10 – Apr 24 | Jun 12 – Jun 26 | — | — |
| Lettuce | Apr 10 – Apr 24 | May 15 – May 29 | May 8 – Jun 12 | Jul 20 – Aug 17 |
| Kale | Apr 10 – Apr 24 | May 8 – May 22 | May 8 – May 22 | Jul 6 – Jul 27 |
| Broccoli | Apr 10 – Apr 24 | May 22 – Jun 5 | — | — |
| Cabbage | Apr 10 – Apr 24 | May 15 – May 29 | — | — |
| Cauliflower | Apr 10 – Apr 24 | May 22 – Jun 5 | — | — |
| Okra | Apr 24 – May 8 | Jun 26 – Jul 10 | Jun 26 – Jul 10 | — |
| Basil | Apr 24 – May 8 | Jun 12 – Jun 26 | — | — |
| Peas | — | — | Apr 24 – May 15 | Jun 22 – Jul 13 |
| Spinach | — | — | Apr 24 – May 15 | Jul 20 – Aug 10 |
| Radishes | — | — | May 1 – Jun 12 | Aug 3 – Aug 24 |
| Cucumbers | May 8 – May 15 | Jun 19 – Jun 26 | Jun 12 – Jun 26 | — |
| Zucchini & Summer Squash | May 8 – May 15 | — | Jun 12 – Jun 26 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 101 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 8 – May 15 | — | Jun 12 – Jun 26 | — |
| Melons & Watermelon | May 8 – May 15 | Jun 19 – Jul 3 | — | — |
| Carrots | — | — | May 15 – Jun 12 | — |
| Beets | — | — | May 15 – Jun 12 | Jul 6 – Jul 20 |
| Potatoes | — | — | May 15 – Jun 5 | — |
| Swiss Chard | — | — | May 22 – Jun 19 | Jul 6 – Jul 20 |
| Cilantro | — | — | May 22 – Jun 12 | Jul 20 – Aug 10 |
| Green Beans | — | — | Jun 12 – Jul 3 | — |
| Sweet Corn | — | — | Jun 12 – Jun 26 | — |
| Sweet Potatoes Warning: Your frost-free season is about 101 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 19 – Jul 10 | — | — |
| Garlic | — | — | — | Aug 31 – Oct 5 |
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 Mystic Lake, MT weather station, 13 km away (elevation 6,545 ft (1,995 m)).
Frost dates near Roscoe
- Fishtail Jun 1 · Sep 11
- Red Lodge Jun 3 · Sep 19
- Nye Jun 1 · Sep 11
- Absarokee May 27 · Sep 14
- Roberts May 29 · Sep 15
- Bearcreek Jun 3 · Sep 19
- Cooke City frost any month
- Silver Gate frost any month
- Boyd May 29 · Sep 15
- Belfry May 18 · Sep 22
Frequently asked questions
When is the last frost in Roscoe, MT?
The median last spring frost in Roscoe, MT is June 5. There is still about a 10% chance of frost after June 21, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Roscoe, MT?
The median first fall frost is September 14, with about a 10% chance of frost before August 31.
How long is the growing season in Roscoe, MT?
About 101 days between the median last spring frost and first fall frost.
What planting zone is Roscoe, MT?
Roscoe, MT is in USDA hardiness zone 5a.