Boyd, MT frost dates
Last spring frostMay 29median date
First fall frostSep 15median date
Growing season109 daysfrost-free
Hardiness zone5aZone 5a
How Boyd compares
- In 8 years out of 10, the last spring frost in Boyd falls between May 14 and June 17, a 34-day window. The first fall frost falls between September 1 and October 1.
- The median last frost is 10 days later than the Montana median of May 19.
- Its 109-day growing season is longer than 20% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 26 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 185 nights a year at or below 32°F.
- Compared with Billings, MT, 57 km away, the last frost here is 25 days later than there and the growing season is 47 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 14 |
| 50% (median) | May 29 |
| 10% (safe for tender plants) | June 17 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 1 |
| 50% (median) | September 15 |
| 90% (late) | October 1 |
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 Boyd, MT
Boyd, MT frost dates — last frost May 29, first frost Sep 15, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 6 to Mar 20Transplant outside: May 1 to May 15
Start indoors: Mar 20 to Apr 3Transplant outside: Jun 12 to Jun 26
Start indoors: Mar 20 to Apr 3Transplant outside: Jun 12 to Jun 26
Start indoors: Apr 3 to Apr 17Transplant outside: Jun 5 to Jun 19
Start indoors: Apr 3 to Apr 17Transplant outside: May 8 to May 22Sow outdoors: May 1 to Jun 5Plant for fall: Jul 21 to Aug 18
Start indoors: Apr 3 to Apr 17Transplant outside: May 1 to May 15Sow outdoors: May 1 to May 15Plant for fall: Jul 7 to Jul 28
Start indoors: Apr 3 to Apr 17Transplant outside: May 15 to May 29
Start indoors: Apr 3 to Apr 17Transplant outside: May 8 to May 22
Start indoors: Apr 3 to Apr 17Transplant outside: May 15 to May 29
Start indoors: Apr 17 to May 1Transplant outside: Jun 19 to Jul 3Sow outdoors: Jun 19 to Jul 3
Start indoors: Apr 17 to May 1Transplant outside: Jun 5 to Jun 19
Sow outdoors: Apr 17 to May 8Plant for fall: Jun 23 to Jul 14
Sow outdoors: Apr 17 to May 8Plant for fall: Jul 21 to Aug 11
Sow outdoors: Apr 24 to Jun 5Plant for fall: Aug 4 to Aug 25
Start indoors: May 1 to May 8Transplant outside: Jun 12 to Jun 19Sow outdoors: Jun 5 to Jun 19
Start indoors: May 1 to May 8Sow outdoors: Jun 5 to Jun 19Plant for fall: Jul 7 to Jul 21
Start indoors: May 1 to May 8Sow outdoors: Jun 5 to Jun 19
Start indoors: May 1 to May 8Transplant outside: Jun 12 to Jun 26
Sow outdoors: May 8 to Jun 5Plant for fall: Jun 23 to Jul 7
Sow outdoors: May 8 to Jun 5Plant for fall: Jul 7 to Jul 21
Sow outdoors: May 8 to May 29
Sow outdoors: May 15 to Jun 12Plant for fall: Jul 7 to Jul 21
Sow outdoors: May 15 to Jun 5Plant for fall: Jul 21 to Aug 11
Sow outdoors: Jun 5 to Jun 26
Sow outdoors: Jun 5 to Jun 19
Transplant outside: Jun 12 to Jul 3
Plant for fall: Sep 1 to Oct 6
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Boyd, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 6 – Mar 20 | May 1 – May 15 | — | — |
| Peppers | Mar 20 – Apr 3 | Jun 12 – Jun 26 | — | — |
| Eggplant | Mar 20 – Apr 3 | Jun 12 – Jun 26 | — | — |
| Tomatoes | Apr 3 – Apr 17 | Jun 5 – Jun 19 | — | — |
| Lettuce | Apr 3 – Apr 17 | May 8 – May 22 | May 1 – Jun 5 | Jul 21 – Aug 18 |
| Kale | Apr 3 – Apr 17 | May 1 – May 15 | May 1 – May 15 | Jul 7 – Jul 28 |
| Broccoli | Apr 3 – Apr 17 | May 15 – May 29 | — | — |
| Cabbage | Apr 3 – Apr 17 | May 8 – May 22 | — | — |
| Cauliflower | Apr 3 – Apr 17 | May 15 – May 29 | — | — |
| Okra | Apr 17 – May 1 | Jun 19 – Jul 3 | Jun 19 – Jul 3 | — |
| Basil | Apr 17 – May 1 | Jun 5 – Jun 19 | — | — |
| Peas | — | — | Apr 17 – May 8 | Jun 23 – Jul 14 |
| Spinach | — | — | Apr 17 – May 8 | Jul 21 – Aug 11 |
| Radishes | — | — | Apr 24 – Jun 5 | Aug 4 – Aug 25 |
| Cucumbers | May 1 – May 8 | Jun 12 – Jun 19 | Jun 5 – Jun 19 | — |
| Zucchini & Summer Squash | May 1 – May 8 | — | Jun 5 – Jun 19 | Jul 7 – Jul 21 |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 109 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 1 – May 8 | — | Jun 5 – Jun 19 | — |
| Melons & Watermelon | May 1 – May 8 | Jun 12 – Jun 26 | — | — |
| Carrots | — | — | May 8 – Jun 5 | Jun 23 – Jul 7 |
| Beets | — | — | May 8 – Jun 5 | Jul 7 – Jul 21 |
| Potatoes | — | — | May 8 – May 29 | — |
| Swiss Chard | — | — | May 15 – Jun 12 | Jul 7 – Jul 21 |
| Cilantro | — | — | May 15 – Jun 5 | Jul 21 – Aug 11 |
| Green Beans | — | — | Jun 5 – Jun 26 | — |
| Sweet Corn | — | — | Jun 5 – Jun 19 | — |
| Sweet Potatoes Warning: Your frost-free season is about 109 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 12 – Jul 3 | — | — |
| Garlic | — | — | — | Sep 1 – Oct 6 |
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 Joliet, MT weather station, 5 km away (elevation 3,839 ft (1,170 m)).
Frost dates near Boyd
- Joliet May 29 · Sep 15
- Roberts May 29 · Sep 15
- Fromberg May 14 · Sep 24
- Edgar May 29 · Sep 15
- Park City May 29 · Sep 15
- Bridger May 14 · Sep 24
- Columbus May 27 · Sep 14
- Absarokee May 27 · Sep 14
- Red Lodge Jun 3 · Sep 19
- Laurel May 5 · Oct 3
Frequently asked questions
When is the last frost in Boyd, MT?
The median last spring frost in Boyd, MT is May 29. There is still about a 10% chance of frost after June 17, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Boyd, MT?
The median first fall frost is September 15, with about a 10% chance of frost before September 1.
How long is the growing season in Boyd, MT?
About 109 days between the median last spring frost and first fall frost.
What planting zone is Boyd, MT?
Boyd, MT is in USDA hardiness zone 5a.