Cosmos Seeds,
Cosmic Yellow

Plant Cosmic Yellow cosmos after the last frost, when soil temperatures reach at least 60 F. Alternatively, you can start seeds indoors 3-4 weeks before the last frost. Since it is sensitive to frost, check your local last frost date before direct sowing or transplanting seedlings outdoors. This variety begins to bloom 50-60 days after sowing and will continue flowering until the first frost. Learn more about frost dates by checking out our blog post, 'Our Experts Answer Questions, Share Resources.'

Sow seeds 1/8-1/4 inch deep in well-draining soil and press them lightly into the surface. Do not bury them too deeply, as cosmos seeds require light to germinate. Space plants about 10 inches apart for good airflow. Germination takes 7-14 days at temperatures between 60-75 F. If starting indoors, be careful to transplant only when the temperatures are consistently warm.

Make sure that the plant receives 6-8 hours of full sun every day. It is drought tolerant once established and should be watered only when the soil is completely dry. Overwatering can weaken the plant and lead to leggy growth. Too much nitrogen will cause excessive foliage growth and fewer flowers, so avoid excessive fertilization. In windy locations, light staking may be needed for support.

• 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.