FrostCal

When to Plant Dahlias in Montana

In a typical Montana location, plant outdoors May 21 – Jun 4. Across the state, the outdoor planting window starts as early as May 12 in Laurel and as late as Jun 20 in Butte.

Method Plant out (slips, crowns, or tubers)
Days to maturity 90–120 days

Plant tubers 1-3 weeks after last frost once soil is warm (60F+); very frost-sensitive.

Dahlias Planting Dates by City

CityPlant outdoors
BillingsMay 17 – May 31
MissoulaMay 17 – May 31
Great FallsMay 13 – May 27
BozemanJun 2 – Jun 16
ButteJun 20 – Jul 4
HelenaMay 16 – May 30
KalispellJun 7 – Jun 21
HavreMay 22 – Jun 5
AnacondaJun 8 – Jun 22
Miles CityMay 15 – May 29
Helena Valley SoutheastMay 16 – May 30
BelgradeJun 2 – Jun 16
Helena Valley West CentralMay 16 – May 30
EvergreenJun 7 – Jun 21
LivingstonJun 3 – Jun 17
WhitefishMay 23 – Jun 6
LaurelMay 12 – May 26
SidneyMay 18 – Jun 1
LockwoodMay 17 – May 31
LewistownMay 21 – Jun 4

Showing the 20 most populous of 20 Montana cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all Montana cities.

Frequently Asked Questions

When should I plant dahlias in Montana?

In a typical Montana location, plant outdoors May 21 – Jun 4. Across the state, the outdoor planting window starts as early as May 12 in Laurel and as late as Jun 20 in Butte.

When is the last frost in Montana?

The average last spring frost in Montana ranges from May 5 in Laurel to June 13 in Butte, based on NOAA 1991–2020 climate normals.

How long do dahlias take to grow?

Dahlias typically take 90–120 days from planting to harvest. Plant tubers 1-3 weeks after last frost once soil is warm (60F+); very frost-sensitive.

Other Crops in Montana

When to plant dahlias in other states

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