Cosmos Planting Guide
Airy, cottage-garden annual with feathery foliage and daisy-like flowers
Best Time and Place to Plant Cosmos
In USDA zone 7, the typical spring window is April 1 to May 15. Cooler zones usually plant later; warmer zones plant earlier.
Plant Cosmos in a spot with 6+ hours of direct sun, soil warmed to 60F to 90F, and enough room for 12 inches between plants and 18 inches between rows.
Planting Windows by Zone
| Zone | Spring | Fall |
|---|---|---|
| Zone 1 | May 15 to June 15 | Varies |
| Zone 2 | May 10 to June 10 | Varies |
| Zone 3 | May 1 to June 1 | Varies |
| Zone 4 | April 20 to May 30 | Varies |
| Zone 5 | April 15 to May 25 | Varies |
| Zone 6 | April 10 to May 20 | Varies |
| Zone 7 | April 1 to May 15 | Varies |
| Zone 8 | March 20 to May 10 | Varies |
| Zone 9 | March 10 to May 1 | August 1 to September 15 |
| Zone 10 | February 15 to April 15 | August 15 to October 1 |
| Zone 11 | January 15 to March 15 | September 1 to November 1 |
| Zone 12 | January 1 to March 1 | October 1 to December 1 |
| Zone 13 | Year-round to Year-round | Varies |
Spacing and Care
- Planting depth: 0.25 inches deep
- Spacing: 12 inches apart, 18 inches between rows
- Soil temperature: 60F to 90F
- Sunlight: 6+ hours
- Watering: 0.5-1 inch per week; drought tolerant; thrives in lean soil
- Days to harvest: 60
Fertilization
- Compost organic: Light 0.5 inch dressing only — too much fertilizer causes few flowers
Companion Plants
- Marigold
- Zinnias
- Tomatoes
Avoid Planting Near
No avoid-planting conflicts are listed yet.
Harvest Signs
- Blooms are fully open in pink, white, or crimson
- Deadhead to extend blooming season
- Allow some flowers to go to seed for self-sowing
- Cut flowers before fully open for longest vase life
FAQs
When should I plant Cosmos?
Cosmos planting depends on your USDA hardiness zone. In USDA zone 7, the typical spring window is April 1 to May 15. Cooler zones usually plant later; warmer zones plant earlier.
What is the best time of year to plant Cosmos?
The best time of year to plant Cosmos is when your zone planting window is open and soil temperatures are around 60F to 90F. In USDA zone 7, the typical spring window is April 1 to May 15. Cooler zones usually plant later; warmer zones plant earlier.
Where is the best place to plant Cosmos?
Plant Cosmos in a spot with 6+ hours of direct sun, soil warmed to 60F to 90F, and enough room for 12 inches between plants and 18 inches between rows.
How far apart should I plant Cosmos?
Plant Cosmos about 12 inches apart, with rows around 18 inches apart.
What grows well with Cosmos?
Cosmos is commonly paired with Marigold, Zinnias, Tomatoes.