Sow seeds outdoors 1 or in colder climates sow seeds indoors. 2 Will reseed readily.
Try to aim for a seed spacing of at least 0.98 inches (2.5 cm) and sow at a depth of around 0.25 inches (0.64 cm). Soil temperature should be kept higher than 20°C / 68°F to ensure good germination.By our calculations*, you should look at sowing Garden Cosmos about 28 days before your last frost date .
Transplant outdoors after ground has warmed. 2
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Garden Cosmos is a half hardy plant.Put cut flowers in deep water immediately to prevent wilting. 1
Seeds are very easily collected when dry. I simply pick the seeds and scatter them where I want them to grow.
Seed viability is three years.
These estimates for how long Garden Cosmos takes to sprout, grow and harvest are from real observations from real gardeners, right around the world.
Average 7 days | Min 1 days | Max 21 days (178)
Average 21 days | Min 13 days | Max 71 days (9)
Average 54 days | Min 32 days | Max 160 days (8)
Our when to plant Garden Cosmos estimates are relative to your last frost date.
The botanical epithet is from the Latin bipinnatus meaning “staunch” or “like two small wings”.4
Cosmos