FrostCal

When to Plant Zinnias in Montana

In a typical Montana location, start seeds indoors Apr 16 – Apr 23, then sow outdoors May 21 – Jun 4, then transplant outdoors May 21 – May 28. Across the state, the outdoor planting window starts as early as May 12 in Laurel and as late as Jun 20 in Butte.

Method Direct sow
Days to maturity 60–70 days

Frost-tender; direct sow 1-3 weeks after last frost, or start indoors 3-4 weeks early for earlier blooms.

Zinnias Planting Dates by City

CityStart indoorsDirect sowTransplant
BillingsApr 12 – Apr 19May 17 – May 31May 17 – May 24
MissoulaApr 12 – Apr 19May 17 – May 31May 17 – May 24
Great FallsApr 8 – Apr 15May 13 – May 27May 13 – May 20
BozemanApr 28 – May 5Jun 2 – Jun 16Jun 2 – Jun 9
ButteMay 16 – May 23Jun 20 – Jul 4Jun 20 – Jun 27
HelenaApr 11 – Apr 18May 16 – May 30May 16 – May 23
KalispellMay 3 – May 10Jun 7 – Jun 21Jun 7 – Jun 14
HavreApr 17 – Apr 24May 22 – Jun 5May 22 – May 29
AnacondaMay 4 – May 11Jun 8 – Jun 22Jun 8 – Jun 15
Miles CityApr 10 – Apr 17May 15 – May 29May 15 – May 22
Helena Valley SoutheastApr 11 – Apr 18May 16 – May 30May 16 – May 23
BelgradeApr 28 – May 5Jun 2 – Jun 16Jun 2 – Jun 9
Helena Valley West CentralApr 11 – Apr 18May 16 – May 30May 16 – May 23
EvergreenMay 3 – May 10Jun 7 – Jun 21Jun 7 – Jun 14
LivingstonApr 29 – May 6Jun 3 – Jun 17Jun 3 – Jun 10
WhitefishApr 18 – Apr 25May 23 – Jun 6May 23 – May 30
LaurelApr 7 – Apr 14May 12 – May 26May 12 – May 19
SidneyApr 13 – Apr 20May 18 – Jun 1May 18 – May 25
LockwoodApr 12 – Apr 19May 17 – May 31May 17 – May 24
LewistownApr 16 – Apr 23May 21 – Jun 4May 21 – May 28

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 zinnias in Montana?

In a typical Montana location, start seeds indoors Apr 16 – Apr 23, then sow outdoors May 21 – Jun 4, then transplant outdoors May 21 – May 28. 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 zinnias take to grow?

Zinnias typically take 60–70 days from planting to harvest. Frost-tender; direct sow 1-3 weeks after last frost, or start indoors 3-4 weeks early for earlier blooms.

Other Crops in Montana

When to plant zinnias in other states

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