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Cosmos

Cut Flower Care Guide

Cosmos are effortless, airy annuals that fill the gap in summer bouquets with their delicate, dancing blooms on wiry stems. They thrive in poor soil (rich soil produces foliage, not flowers) and bloom prolifically from midsummer through frost. Cosmos bipinnatus types are the classic tall cut flower; C. sulphureus offers warm tones.

🌱 Planting Guide

When to Plant Direct sow after last frost, or start indoors 4–6 weeks before last frost. Succession sow every 3 weeks.

Planting Depth 1/4 inch deep; barely cover seeds

Spacing 12–18 inches between plants; 24–36 inches between rows

Soil Average to poor, well-drained soil. Too-rich soil produces lanky plants with few blooms.

Sunlight Full sun — 6+ hours

💡 Tips

Don't amend soil for cosmos — they bloom best in lean conditions
Direct sowing works great — they transplant fine too
Pinch when 12 inches tall for bushier plants and more stems
Support netting keeps tall varieties upright
Dazzler, Cupcakes, and Double Click are excellent cut flower varieties

📅 Month-by-Month Care Calendar

Jan

Order seeds. Plan succession sowing schedule.

Feb

Finalize seed orders. Prepare planting maps.

Mar

Start first batch indoors 4–6 weeks before last frost (optional).

Apr

Continue indoor growing. Prepare beds — don't add fertilizer.

May

Direct sow after last frost. Transplant indoor starts. Install netting.

Jun

Plants growing rapidly. Pinch at 12 inches. Sow second succession.

Jul

Begin harvesting. Sow final succession. Deadhead to keep blooms coming.

Aug

Peak harvest. Cut daily. Continue deadheading.

Sep

Harvest continues. Save seeds from best blooms. Plants still producing well.

Oct

Harvest until frost. Collect final seeds. Pull plants after killing frost.

Nov

Clean up beds. Save dried seed heads. Compost spent plants.

Dec

Review season. Plan next year's cosmos varieties and succession schedule.