Troy, MT frost dates
Last spring frostMay 14median date
First fall frostSep 25median date
Growing season134 daysfrost-free
Hardiness zone6aZone 6a
How Troy compares
- In 8 years out of 10, the last spring frost in Troy falls between April 29 and May 31, a 32-day window. The first fall frost falls between September 9 and October 9.
- The median last frost is 5 days earlier than the Montana median of May 19.
- Its 134-day growing season is longer than 68% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 15 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 152 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 29 |
| 50% (median) | May 14 |
| 10% (safe for tender plants) | May 31 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 9 |
| 50% (median) | September 25 |
| 90% (late) | October 9 |
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 Troy, MT
Troy, MT frost dates — last frost May 14, first frost Sep 25, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Feb 19 to Mar 5Transplant outside: Apr 16 to Apr 30
Start indoors: Mar 5 to Mar 19Transplant outside: May 28 to Jun 11
Start indoors: Mar 5 to Mar 19Transplant outside: May 28 to Jun 11
Start indoors: Mar 19 to Apr 2Transplant outside: May 21 to Jun 4
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 23 to May 7Sow outdoors: Apr 16 to May 21Plant for fall: Jul 31 to Aug 28
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 16 to Apr 30Sow outdoors: Apr 16 to Apr 30Plant for fall: Jul 17 to Aug 7
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 30 to May 14Plant for fall: Jun 19 to Jul 10
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 23 to May 7Plant for fall: Jun 19 to Jul 10
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 30 to May 14Plant for fall: Jun 19 to Jul 10
Start indoors: Apr 2 to Apr 16Transplant outside: Jun 4 to Jun 18Sow outdoors: Jun 4 to Jun 18
Start indoors: Apr 2 to Apr 16Transplant outside: May 21 to Jun 4
Sow outdoors: Apr 2 to Apr 23Plant for fall: Jul 3 to Jul 24
Sow outdoors: Apr 2 to Apr 23Plant for fall: Jul 31 to Aug 21
Sow outdoors: Apr 9 to May 21Plant for fall: Aug 14 to Sep 4
Start indoors: Apr 16 to Apr 23Transplant outside: May 28 to Jun 4Sow outdoors: May 21 to Jun 4Plant for fall: Jul 10 to Jul 24
Start indoors: Apr 16 to Apr 23Sow outdoors: May 21 to Jun 4Plant for fall: Jul 17 to Jul 31
Start indoors: Apr 16 to Apr 23Sow outdoors: May 21 to Jun 4
Start indoors: Apr 16 to Apr 23Transplant outside: May 28 to Jun 11
Sow outdoors: Apr 23 to May 21Plant for fall: Jul 3 to Jul 17
Sow outdoors: Apr 23 to May 21Plant for fall: Jul 17 to Jul 31
Sow outdoors: Apr 23 to May 14
Sow outdoors: Apr 30 to May 28Plant for fall: Jul 17 to Jul 31
Sow outdoors: Apr 30 to May 21Plant for fall: Jul 31 to Aug 21
Sow outdoors: May 21 to Jun 11Plant for fall: Jul 10 to Jul 24
Sow outdoors: May 21 to Jun 4
Transplant outside: May 28 to Jun 18
Plant for fall: Sep 11 to Oct 16
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Troy, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 19 – Mar 5 | Apr 16 – Apr 30 | — | — |
| Peppers | Mar 5 – Mar 19 | May 28 – Jun 11 | — | — |
| Eggplant | Mar 5 – Mar 19 | May 28 – Jun 11 | — | — |
| Tomatoes | Mar 19 – Apr 2 | May 21 – Jun 4 | — | — |
| Lettuce | Mar 19 – Apr 2 | Apr 23 – May 7 | Apr 16 – May 21 | Jul 31 – Aug 28 |
| Kale | Mar 19 – Apr 2 | Apr 16 – Apr 30 | Apr 16 – Apr 30 | Jul 17 – Aug 7 |
| Broccoli | Mar 19 – Apr 2 | Apr 30 – May 14 | — | Jun 19 – Jul 10 |
| Cabbage | Mar 19 – Apr 2 | Apr 23 – May 7 | — | Jun 19 – Jul 10 |
| Cauliflower | Mar 19 – Apr 2 | Apr 30 – May 14 | — | Jun 19 – Jul 10 |
| Okra | Apr 2 – Apr 16 | Jun 4 – Jun 18 | Jun 4 – Jun 18 | — |
| Basil | Apr 2 – Apr 16 | May 21 – Jun 4 | — | — |
| Peas | — | — | Apr 2 – Apr 23 | Jul 3 – Jul 24 |
| Spinach | — | — | Apr 2 – Apr 23 | Jul 31 – Aug 21 |
| Radishes | — | — | Apr 9 – May 21 | Aug 14 – Sep 4 |
| Cucumbers | Apr 16 – Apr 23 | May 28 – Jun 4 | May 21 – Jun 4 | Jul 10 – Jul 24 |
| Zucchini & Summer Squash | Apr 16 – Apr 23 | — | May 21 – Jun 4 | Jul 17 – Jul 31 |
| Winter Squash & Pumpkins | Apr 16 – Apr 23 | — | May 21 – Jun 4 | — |
| Melons & Watermelon | Apr 16 – Apr 23 | May 28 – Jun 11 | — | — |
| Carrots | — | — | Apr 23 – May 21 | Jul 3 – Jul 17 |
| Beets | — | — | Apr 23 – May 21 | Jul 17 – Jul 31 |
| Potatoes | — | — | Apr 23 – May 14 | — |
| Swiss Chard | — | — | Apr 30 – May 28 | Jul 17 – Jul 31 |
| Cilantro | — | — | Apr 30 – May 21 | Jul 31 – Aug 21 |
| Green Beans | — | — | May 21 – Jun 11 | Jul 10 – Jul 24 |
| Sweet Corn | — | — | May 21 – Jun 4 | — |
| Sweet Potatoes | — | May 28 – Jun 18 | — | — |
| Garlic | — | — | — | Sep 11 – Oct 16 |
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 Troy, MT weather station, 2 km away (elevation 1,929 ft (588 m)).
Frost dates near Troy
- Libby May 10 · Sep 26
- Noxon May 20 · Sep 20
- Heron May 20 · Sep 20
- Rexford May 11 · Sep 27
- Eureka May 11 · Sep 27
- Trout Creek May 20 · Sep 21
- Trego May 16 · Sep 18
- Fortine May 16 · Sep 18
- Stryker May 16 · Sep 18
- Marion frost any month
Frequently asked questions
When is the last frost in Troy, MT?
The median last spring frost in Troy, MT is May 14. There is still about a 10% chance of frost after May 31, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Troy, MT?
The median first fall frost is September 25, with about a 10% chance of frost before September 9.
How long is the growing season in Troy, MT?
About 134 days between the median last spring frost and first fall frost.
What planting zone is Troy, MT?
Troy, MT is in USDA hardiness zone 6a.