When to Plant Cosmos in Ohio
Direct Sow Outdoors
Friday, April 10, 2026
State
Ohio
USDA Zones
5b, 6a, 6b, 7a
Avg Last Frost
Friday, April 10, 2026
Cities Covered
1059
Ohio Planting Schedule by Zone
Ohio spans 4 zones — find yours below for the most accurate dates.
| Zone | Last Frost | Direct Sow |
|---|---|---|
| 5b | Saturday, April 25, 2026 | Saturday, April 25, 2026 |
| 6a | Monday, April 20, 2026 | Monday, April 20, 2026 |
| 6b | Wednesday, April 15, 2026 | Wednesday, April 15, 2026 |
| 7a | Friday, April 10, 2026 | Friday, April 10, 2026 |
Dates based on average last frost. Check your local forecast before planting.
🌿 About Cosmos
🤝 Companion Plants for Cosmos
Good Companions
Growing Cosmos in Ohio: Complete Guide
Cosmos (Cosmos bipinnatus) is a crop that grows best when sown directly in the garden. In Ohio, the right time to direct sow is around Friday, April 10, 2026, once soil temperatures are consistently warm enough for germination.
Because Ohio stretches across 4 USDA hardiness zones (5b, 6a, 6b, 7a), planting windows can shift by as much as two to four weeks from one end of the state to the other. Gardeners in the warmer southern zones can start earlier, while those in cooler northern zones should wait until the zone table above shows their last frost has passed.
With 60 days to maturity, Cosmos fits comfortably within Ohio's growing season in most zones. In the warmest parts of the state, a second planting later in the season may be possible.
Cosmos requires full sun (6-8 hours) and low-moderate moisture. Most of Ohio receives adequate sunlight during the growing season, though gardeners in humid eastern regions should watch for fungal issues and ensure good air circulation.
For the most precise planting dates tailored to your exact location, enter your ZIP code on our planting calendar or use the zone table above to find the schedule for your area of Ohio.
Frequently Asked Questions
When should I plant Cosmos in Ohio?
In Ohio, direct sow Cosmos outdoors around Friday, April 10, 2026. Ohio spans zones 5b–7a, so gardeners in warmer zones can plant earlier.
What is the last frost date in Ohio?
Ohio spans 4 USDA zones (5b, 6a, 6b, 7a), so last frost dates vary by region. Sparta (5b) sees frost until around Saturday, April 25, 2026, while Cleveland, Lakewood, Rocky River (7a) is frost-free much earlier.
How long does Cosmos take to grow in Ohio?
Cosmos takes about 60 days from transplant (or direct sow) to harvest. In Ohio's longer-season zones, a second planting in late summer may be possible.
What USDA zones does Ohio cover for Cosmos?
Ohio includes zones 5b, 6a, 6b, 7a. Cosmos grows well across all of these zones with adjusted timing — use the zone table above to find the right dates for your part of the state.
Find Precise Dates for Your City
Select a city for exact planting dates based on local frost records.