Cosmos Seeds,
Cosmic Red

Plant cosmos after the last frost, when soil temperatures are consistently above 60 F. In colder climates, start seeds 3-4 weeks before the last expected frost and transplant them outdoors once the weather has warmed. In warm regions, cosmos can be grown nearly year-round. To determine the best planting time, check your local area's frost dates. If you're not sure how to do that, refer to our blog post 'Our Experts Answer Questions, Share Resources.'

Lightly press the seeds into the soil 1/8-1/4 inch deep, but do not cover them heavily, as they need light to germinate. Space plants about 10 inches apart for good airflow. Keep the soil evenly moist until seeds germinate, usually within 7-14 days. If you’re starting indoors, transplant seedlings outdoors only after the risk of frost has passed, being careful not to disturb the roots.

Make sure that you’ve chosen a location that receives 6-8 hours of direct sunlight daily. Avoid excessive fertilization, as too much nitrogen encourages leaf growth instead of flowers. Once established, cosmos are drought tolerant and require minimal watering. Overwatering can lead to weak stems and fewer blooms. Taller plants may need staking in windy areas. If plants become too tall or leggy, trim them back by one-third for bushier growth.

• Cosmos are insect pollinated, and there may be some crossing between varieties in the garden. You can enjoy the mixing or use caging techniques and hand pollination to avoid crossing.
• Saving seeds from cosmos is easy: simply allow the heads to brown and dry on plants and collect seeds. Store in a cool, dry, dark place over winter.