Cosmos Growing Guide
Asteraceae family
Days to Harvest55 days
SunlightFull Sun
Frost ToleranceNone
Spacing12/sqft
Germination5-10 days
HardinessTender
Germ. Temp75°F
Start Indoors4 weeks before last frost
Growth Stages
- Seedling
- Establishing
- Budding
- Blooming
Planting Dates by Zone
| Zone | Start Indoors | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 1a | Apr 27 | Jun 1 | Jun 1 | Jul 26 |
| Zone 1b | Apr 27 | Jun 1 | Jun 1 | Jul 26 |
| Zone 2a | Apr 17 | May 22 | May 22 | Jul 16 |
| Zone 2b | Apr 27 | Jun 1 | Jun 1 | Jul 26 |
| Zone 3a | Apr 24 | May 29 | May 29 | Jul 23 |
| Zone 3b | Apr 17 | May 22 | May 22 | Jul 16 |
| Zone 4a | Apr 7 | May 12 | May 12 | Jul 6 |
| Zone 4b | Apr 3 | May 8 | May 8 | Jul 2 |
| Zone 5a | Mar 31 | May 5 | May 5 | Jun 29 |
| Zone 5b | Mar 31 | May 5 | May 5 | Jun 29 |
| Zone 6a | Mar 31 | May 5 | May 5 | Jun 29 |
| Zone 6b | Mar 18 | Apr 22 | Apr 22 | Jun 16 |
| Zone 7a | Mar 18 | Apr 22 | Apr 22 | Jun 16 |
| Zone 7b | Mar 13 | Apr 17 | Apr 17 | Jun 11 |
| Zone 8a | Mar 8 | Apr 12 | Apr 12 | Jun 6 |
| Zone 8b | Feb 22 | Mar 29 | Mar 29 | May 23 |
| Zone 9a | Feb 20 | Mar 27 | Mar 27 | May 21 |
| Zone 9b | Feb 10 | Mar 17 | Mar 17 | May 11 |
| Zone 10a | Jan 23 | Feb 27 | Feb 27 | Apr 23 |
| Zone 10b | Dec 31 | Feb 4 | Feb 4 | Mar 31 |
| Zone 11a | Dec 31 | Feb 4 | Feb 4 | Mar 31 |
| Zone 11b | Dec 18 | Jan 22 | Jan 22 | Mar 18 |
| Zone 12a | Dec 4 | Jan 8 | Jan 8 | Mar 4 |
| Zone 12b | Dec 4 | Jan 8 | Jan 8 | Mar 4 |
| Zone 13a | Dec 4 | Jan 8 | Jan 8 | Mar 4 |
| Zone 13b | Dec 4 | Jan 8 | Jan 8 | Mar 4 |
Frequently Asked Questions
How long does it take to grow Cosmos?
Cosmos takes approximately 55 days from planting to harvest.
How much sun does Cosmos need?
Cosmos requires full sun (6+ hours direct sunlight per day).
How far apart should I plant Cosmos?
Plant Cosmos at 12/sqft using square foot gardening spacing.
Can Cosmos survive frost?
Cosmos is frost-sensitive and should not be exposed to frost.
How long does Cosmos take to germinate?
Cosmos seeds germinate in 5-10 days at an optimal temperature of 75°F.
When should I start Cosmos seeds indoors?
Start Cosmos seeds indoors 4 weeks before your last frost date, then transplant 1 week after last frost.
Plan Your Cosmos Garden
Track Cosmos from seed to harvest with personalized frost dates, watering recommendations, and companion planting visualization.
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