How to Grow Cosmos

Cosmos

Cosmos bipinnatus

Details

Plant type: annual
Planting season: spring
Height: up to 42"
Site: full sun
Seed depth: 1/8"
Days to germination: 7-10 days at 68-72°F (20-22°C)
Days to maturity: 85-100
Plant spacing: 9-12"
Pinch: when plant is 8-12" tall

Growing Notes

Transplant - Sow into 50-cell plug flats or preferred seedling container 5-7 weeks before planting out, covering seeds lightly. Harden off and transplant out after danger of frost.

Direct seed - Sow after last frost, once soil temperature is above 60°F (16°C), covering seeds lightly. 

Harvest

Harvest when petals are just opening, but not yet flattened. Deadheading is required to have blooms all summer.

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