When to plant Cosmos
Airy, daisy-flowered annuals that bloom for months on poor soil. Rich ground and feeding give you tall leafy plants and few flowers, so plant them lean and leave them alone. They self-sow and are superb for pollinators.
Companions: Most vegetables — draws hoverflies, lacewings, and bees
How to grow Cosmos
Cosmos is best direct-sown straight into the garden, as it dislikes being transplanted. Give it full sun and space plants about 12 inches apart. It takes roughly 60 days from planting to its first harvest, so count that against your frost dates to be sure it can finish. Classic companions include most vegetables — draws hoverflies, lacewings, and bees.
Grower's tip: Thrives on neglect — too-rich soil gives leaves at the expense of flowers.
When to plant Cosmos by USDA zone
Timing shifts with your climate — the same cosmos goes in weeks earlier in a mild zone than a cold one. Find your zone below for its planting window, or open that zone's full calendar.
| Zone | When to plant |
|---|---|
| Zone 1a | Direct sow outdoors Jun 15–Jun 29 |
| Zone 1b | Direct sow outdoors Jun 10–Jun 24 |
| Zone 2a | Direct sow outdoors Jun 5–Jun 19 |
| Zone 2b | Direct sow outdoors May 30–Jun 13 |
| Zone 3a | Direct sow outdoors May 25–Jun 8 |
| Zone 3b | Direct sow outdoors May 20–Jun 3 |
| Zone 4a | Direct sow outdoors May 15–May 29 |
| Zone 4b | Direct sow outdoors May 10–May 24 |
| Zone 5a | Direct sow outdoors May 5–May 19 |
| Zone 5b | Direct sow outdoors Apr 30–May 14 |
| Zone 6a | Direct sow outdoors Apr 21–May 5 |
| Zone 6b | Direct sow outdoors Apr 15–Apr 29 |
| Zone 7a | Direct sow outdoors Apr 7–Apr 21 |
| Zone 7b | Direct sow outdoors Apr 1–Apr 15 |
| Zone 8a | Direct sow outdoors Mar 22–Apr 5 |
| Zone 8b | Direct sow outdoors Mar 15–Mar 29 |
| Zone 9a | Direct sow outdoors Feb 28–Mar 14 |
| Zone 9b | Direct sow outdoors Feb 15–Mar 1 |
| Zone 10a | Direct sow outdoors Jan 31–Feb 14 |
| Zone 10b | Direct sow outdoors Jan 15–Jan 29 |
| Zone 11a | Direct sow outdoors Jan 1–Jan 15 |
| Zone 11b | Direct sow outdoors Jan 1–Jan 15 |
| Zone 12a | Direct sow outdoors Jan 1–Jan 15 |
| Zone 12b | Direct sow outdoors Jan 1–Jan 15 |
| Zone 13a | Direct sow outdoors Jan 1–Jan 15 |
| Zone 13b | Direct sow outdoors Jan 1–Jan 15 |