Last frost date in Helena, Montana
May 9
Average last frost in spring. In an early year (1 in 10) it's over by April 29; in a late year (1 in 10) it comes after May 25.
September 30
Average first frost in fall. 1 year in 10 it comes by September 17.
Source: NOAA U.S. Climate Normals 1991–2020, station Helena Rgnl AP (USW00024144), 2.8 miles from Helena, elevation 3,828 ft. NOAA National Centers for Environmental Information. These are long-term averages, not a forecast.
| Early year | Average | Late year | |
|---|---|---|---|
| Last frost in spring | Apr 29 | May 9 | May 25 |
| First frost in fall | Sept 17 | Sept 30 | Oct 11 |
An early or late year is one in 10: 1 year in 10 the frost comes before the early date, and 1 year in 10 after the late date.
Frost-free days in an average year: 142
Planting calendar for Helena
Fall planting
USDA dates for places whose average first freeze is about September 30 (Helena: September 30).
- PotatoesMay 1 – June 15 (past for this year)
- Cauliflower plantsMay 10 – July 15 (past for this year)
- Cantaloupe (muskmelon)May 15 – June 1 (past for this year)
- New Zealand spinachMay 15 – July 1 (past for this year)
- WatermelonMay 15 – June 1 (past for this year)
- Eggplant plantsMay 20 – June 10 (past for this year)
- SoybeansMay 25 – June 10 (past for this year)
- BeetsJune 1 – July 10 (past for this year)
- Broccoli plantsJune 1 – 30 (past for this year)
- Brussels sprouts plantsJune 1 – 30 (past for this year)
- Cabbage plantsJune 1 – July 10 (past for this year)
- CarrotsJune 1 – July 10 (past for this year)
- Celery and celeriac plantsJune 1 – July 5 (past for this year)
- Chinese cabbageJune 1 – July 15 (past for this year)
- CucumbersJune 1 – July 1 (past for this year)
- DandelionJune 1 – Aug 1 (past for this year)
- Florence fennelJune 1 – July 1 (past for this year)
- Garden peasJune 1 – Aug 1 (past for this year)
- Leaf lettuceJune 1 – Aug 1 (past for this year)
- Lima beansJune 1 – 15 (past for this year)
- OkraJune 1 – July 1 (past for this year)
- ParsleyJune 1 – July 15 (past for this year)
- ParsnipsJune 1 – July 1 (past for this year)
- Peppers plantsJune 1 – July 1 (past for this year)
- RutabagaJune 1 – July 1 (past for this year)
- SalsifyJune 1 – 20 (past for this year)
- Snap beansJune 1 – July 10 (past for this year)
- SorrelJune 1 – July 15 (past for this year)
- Summer squashJune 1 – July 1 (past for this year)
- Sweet cornJune 1 – July 1 (past for this year)
- Swiss chardJune 1 – July 5 (past for this year)
- TomatoesJune 1 – 20 (past for this year)
- TurnipsJune 1 – Aug 1 (past for this year)
- Winter squashJune 1 – 15 (past for this year)
- Witloof chicoryJune 1 – July 1 (past for this year)
- Collards plantsJune 15 – July 15 (past for this year)
- EndiveJune 15 – Aug 1 (past for this year)
- Head lettuce plantsJune 15 – Aug 1 (past for this year)
- KaleJune 15 – July 15 (past for this year)
- KohlrabiJune 15 – July 15 (past for this year)
- Mustard greensJune 15 – Aug 1 (past for this year)
- RadishesJuly 1 – Sept 1 (past for this year)
- SpinachJuly 1 – Aug 15 (past for this year)
- Corn saladJuly 15 – Sept 1 (past for this year)
- Upland cressJuly 15 – Sept 1 (past for this year)
- Rhubarb plantsOct 1 – Nov 1Now
USDA lists chervil and chives, garlic, horseradish, leeks, onion plants, onion seed, onion sets, shallots as generally spring-planted here.
Spring planting
USDA dates for places whose average last freeze is about May 10 (Helena: May 9).
- Cabbage plantsApr 1 – May 15
- Chervil and chivesApr 1 – May 1
- Chinese cabbageApr 1 – May 15
- Corn saladApr 1 – June 1
- DandelionApr 1 – May 1
- Garden peasApr 1 – May 15
- GarlicApr 1 – May 1
- Onion seedApr 1 – May 1
- PotatoesApr 1 – June 1
- RadishesApr 1 – June 1
- Rhubarb plantsApr 1 – May 1
- SpinachApr 1 – June 15
- TurnipsApr 1 – June 1
- Asparagus plantsApr 10 – 30
- KaleApr 10 – May 1
- KohlrabiApr 10 – May 15
- Onion plants plantsApr 10 – May 1
- Onion setsApr 10 – May 1
- ShallotsApr 10 – May 1
- BeetsApr 15 – June 15
- Broccoli plantsApr 15 – June 1
- Brussels sprouts plantsApr 15 – June 1
- Cauliflower plantsApr 15 – May 15
- Collards plantsApr 15 – June 1
- EndiveApr 15 – May 15
- Florence fennelApr 15 – May 15
- Head lettuce plantsApr 15 – May 15
- Horseradish plantsApr 15 – May 15
- Leaf lettuceApr 15 – June 15
- LeeksApr 15 – May 15
- Mustard greensApr 15 – June 1
- ParsleyApr 15 – May 15
- ParsnipsApr 15 – May 15
- SalsifyApr 15 – June 1
- SorrelApr 15 – June 1
- CarrotsApr 20 – June 15
- Celery and celeriac plantsApr 20 – June 15
- Swiss chardApr 20 – June 15
- Upland cressApr 20 – May 20
- RutabagaMay 1 – June 1
- New Zealand spinachMay 10 – June 15
- Snap beansMay 10 – June 30
- Summer squashMay 10 – June 10
- Sweet cornMay 10 – June 1
- TomatoesMay 15 – June 10
- CucumbersMay 20 – June 15
- Eggplant plantsMay 20 – June 15
- OkraMay 20 – June 10
- Peppers plantsMay 20 – June 10
- Lima beansMay 25 – June 15
- SoybeansMay 25 – June 10
- Cantaloupe (muskmelon)June 1 – 15
- WatermelonJune 1 – 15
- Witloof chicoryJune 1 – 20
Planting dates: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” tables 4 and 5 (earliest safe spring and latest safe fall dates), applied to this place's NOAA frost dates. “Plants” means setting out transplants, not sowing seed. How we match the table.
Nearby in Montana
- Butte-Silver Bow (balance) 57 mi · last frost June 13
- Belgrade 69 mi · last frost May 26
- Great Falls 71 mi · last frost May 6
- Bozeman 78 mi · last frost May 26
- Missoula 97 mi · last frost May 10