When to Plant Zinnias in Michigan
The cut-and-come-again champion. The more you cut zinnias, the more they bloom. A cottage garden essential.
The Short Answer
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 |
Zinnias Planting Schedule for Michigan
Upper Peninsula (Zones 4a, 4b, 5a)
Average last frost: May 15 - Jun 5 · Average first frost: Sep 10 - Sep 25
Northern Lower Michigan (Zones 5a, 5b)
Average last frost: May 10 - May 25 · Average first frost: Sep 20 - Oct 5
Southern Michigan (Zones 5b, 6a, 6b)
Average last frost: Apr 25 - May 10 · Average first frost: Oct 1 - Oct 15
Growing Zinnias in Michigan
State-Specific Growing Tips
Direct sow from late May when soil reaches 60°F. Michigan's moderate summer temperatures produce long-lasting blooms. Cut flowers regularly to encourage more production. Space 9-12 inches apart in full sun.
Recommended Varieties for Michigan
Benary's Giant, State Fair, Queen Lime. Profusion for compact bedding. MSU Extension recommends zinnias as one of the easiest annual flowers from seed.
Common Challenges in Michigan
Powdery mildew in humid summers. Japanese beetles on petals. The crop is fast enough to outgrow most pest damage.
Growing Tips
Water at the base to prevent powdery mildew. Cut flowers just above a leaf node to encourage more branching and blooms.
Companion Planting
Plant zinnias alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026