- Hardiness
- Grown as an annual in every zone
- Light
- Full sun
- Water
- Low, drought tolerant once settled
- Size
- 2 to 5 ft
- Blooms
- Summer to frost
- Colors
- pink, white, magenta
Growing tip. Thrives on neglect. Rich soil and fertilizer give you leaves instead of flowers.
When to plant cosmos by zone
| Zone | Median last / first frost | When to plant |
|---|---|---|
| 3b | May 16 / Sep 25 | Plant outside: May 23 to Jun 27 |
| 4a | May 12 / Sep 28 | Plant outside: May 19 to Jun 23 |
| 4b | May 8 / Oct 1 | Plant outside: May 15 to Jun 19 |
| 5a | May 3 / Oct 5 | Plant outside: May 10 to Jun 14 |
| 5b | May 1 / Oct 10 | Plant outside: May 8 to Jun 12 |
| 6a | Apr 29 / Oct 16 | Plant outside: May 6 to Jun 10 |
| 6b | Apr 22 / Oct 22 | Plant outside: Apr 29 to Jun 3 |
| 7a | Apr 16 / Oct 25 | Plant outside: Apr 23 to May 28 |
| 7b | Apr 5 / Nov 1 | Plant outside: Apr 12 to May 17 |
| 8a | Mar 29 / Nov 7 | Plant outside: Apr 5 to May 10 |
| 8b | Mar 16 / Nov 14 | Plant outside: Mar 23 to Apr 27 |
| 9a | Mar 2 / Nov 26 | Plant outside: Mar 9 to Apr 13 |
| 9b | Feb 1 / Dec 9 | Plant outside: Feb 8 to Mar 15 |
Zones 10 and warmer have little or no frost. There, plant cool-season plants in fall and warm-season plants from late winter.
Similar annual flowers
Zonal geraniumFull sun · Grown as an annual in every zoneSnapdragonFull sun · Grown as an annual in every zoneCelosiaFull sun · Grown as an annual in every zoneLantanaFull sun · Grown as an annual in every zoneMadagascar periwinkleFull sun · Grown as an annual in every zoneNasturtiumFull sun · Grown as an annual in every zone
Frequently asked questions
What zone does cosmos grow in?
Cosmos is grown fresh each year, so it fits every zone. What changes is when you plant. Find your zone by ZIP code.
How much sun does cosmos need?
Full sun. Full sun means at least six hours of direct sun a day; part shade means about three to six.
Hardiness ranges, light and size are typical figures from university extension services and botanic garden plant records; a named variety can differ, so check its tag. Planting dates come from each zone's median frost dates (NOAA 1991 to 2020 climate normals) and the timing rules in how we check.