FrostCal

When to Plant Cosmos in North Dakota

In a typical North Dakota location, start seeds indoors Apr 12 – Apr 19, then sow outdoors May 17 – May 31, then transplant outdoors May 17 – May 24. Across the state, the outdoor planting window starts as early as May 11 in Wahpeton and as late as May 28 in Beulah.

Method Direct sow
Days to maturity 60–90 days

Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early.

Cosmos Planting Dates by City

CityStart indoorsDirect sowTransplant
FargoApr 7 – Apr 14May 12 – May 26May 12 – May 19
BismarckApr 12 – Apr 19May 17 – May 31May 17 – May 24
Grand ForksApr 12 – Apr 19May 17 – May 31May 17 – May 24
MinotApr 12 – Apr 19May 17 – May 31May 17 – May 24
West FargoApr 12 – Apr 19May 17 – May 31May 17 – May 24
WillistonApr 23 – Apr 30May 28 – Jun 11May 28 – Jun 4
DickinsonApr 22 – Apr 29May 27 – Jun 10May 27 – Jun 3
MandanApr 15 – Apr 22May 20 – Jun 3May 20 – May 27
JamestownApr 10 – Apr 17May 15 – May 29May 15 – May 22
WahpetonApr 6 – Apr 13May 11 – May 25May 11 – May 18
Devils LakeApr 8 – Apr 15May 13 – May 27May 13 – May 20
Watford CityApr 11 – Apr 18May 16 – May 30May 16 – May 23
Valley CityApr 15 – Apr 22May 20 – Jun 3May 20 – May 27
Minot Air Force BaseApr 13 – Apr 20May 18 – Jun 1May 18 – May 25
GraftonApr 6 – Apr 13May 11 – May 25May 11 – May 18
LincolnApr 16 – Apr 23May 21 – Jun 4May 21 – May 28
BeulahApr 23 – Apr 30May 28 – Jun 11May 28 – Jun 4
RugbyApr 19 – Apr 26May 24 – Jun 7May 24 – May 31
StanleyApr 19 – Apr 26May 24 – Jun 7May 24 – May 31
HoraceApr 6 – Apr 13May 11 – May 25May 11 – May 18

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

Frequently Asked Questions

When should I plant cosmos in North Dakota?

In a typical North Dakota location, start seeds indoors Apr 12 – Apr 19, then sow outdoors May 17 – May 31, then transplant outdoors May 17 – May 24. Across the state, the outdoor planting window starts as early as May 11 in Wahpeton and as late as May 28 in Beulah.

When is the last frost in North Dakota?

The average last spring frost in North Dakota ranges from May 4 in Wahpeton to May 21 in Beulah, based on NOAA 1991–2020 climate normals.

How long do cosmos take to grow?

Cosmos typically take 60–90 days from planting to harvest. Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early.

Other Crops in North Dakota

When to plant cosmos in other states

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