Annual Flower

When to Plant Cosmos in Michigan

Delicate, daisy-like blooms that dance in the breeze. Cosmos thrive in poor soil and practically grow themselves.

The Short Answer

Cosmos bloom reliably in Michigan's summer and fall, providing graceful color with zero maintenance. The crop's self-seeding habit means volunteer cosmos appear each spring.

Michigan Frost Dates

Your planting dates depend on which part of Michigan you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Upper Peninsula 4a, 4b, 5a May 15 - Jun 5 Sep 10 - Sep 25
Northern Lower Michigan 5a, 5b May 10 - May 25 Sep 20 - Oct 5
Southern Michigan 5b, 6a, 6b Apr 25 - May 10 Oct 1 - Oct 15

Cosmos Planting Schedule for Michigan

Upper Peninsula (Zones 4a, 4b, 5a)

Average last frost: May 15 - Jun 5 · Average first frost: Sep 10 - Sep 25

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Northern Lower Michigan (Zones 5a, 5b)

Average last frost: May 10 - May 25 · Average first frost: Sep 20 - Oct 5

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Southern Michigan (Zones 5b, 6a, 6b)

Average last frost: Apr 25 - May 10 · Average first frost: Oct 1 - Oct 15

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Growing Cosmos in Michigan

State-Specific Growing Tips

Direct sow from late May. Poor soil, full sun, minimal water. Cosmos are one of the easiest flowers for Michigan beginners. Let some go to seed for next year.

Recommended Varieties for Michigan

Sensation Mix, Double Click, Bright Lights.

Common Challenges in Michigan

Tall varieties may need staking. Otherwise pest and disease free.

Growing Tips

Don't over-fertilize — rich soil produces more leaves and fewer flowers. Let some flowers go to seed for next year's crop.

Companion Planting

Plant cosmos alongside these companions for better growth:

Tomatoes Squash

The Bottom Line

Cosmos can be grown successfully in Michigan with proper attention to regional frost dates and local growing conditions. Timing varies across the state — Upper Peninsula gardeners work with a last frost around May 15 - Jun 5, while Southern Michigan sees frost end around Apr 25 - May 10. Choose varieties suited to your region, amend your soil based on its specific needs, and monitor for the pests and diseases most common in your area. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Cosmos Growing Guide National planting guide with all states Michigan Planting Calendar All plants for Michigan Cosmos in Alabama Alabama planting dates Cosmos in Alaska Alaska planting dates Cosmos in Arizona Arizona planting dates Cosmos in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

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