Cosmos Seeds,
Cosmic Orange

Cosmos should be planted after the last frost when soil temperatures reach at least 60 F. In regions with short growing seasons, start seeds 3-4 weeks before the last expected frost and transplant them outdoors once the weather has warmed. In warm climates, cosmos should be sown in place mid-spring. To find the best planting time, check your local area's frost dates. If you're not sure how to do that, consult our blog post 'Our Experts Answer Questions, Share Resources.'

Press the seeds lightly into the soil 1/8-1/4 inch deep but do not cover heavily, as cosmos require light to germinate. Space plants about 10 inches apart to allow for good air circulation. Keep the soil evenly moist until seeds germinate, typically within 7-14 days. If starting indoors, transplant seedlings outdoors only once they are strong enough and the weather has warmed. Be careful when transplanting to avoid disturbing the roots.

Cosmos thrive in full sun, requiring at least 6-8 hours of direct sunlight daily. Avoid excessive fertilization, as it can cause leafy growth instead of flowers. Once established, cosmos are drought tolerant and require minimal watering. Overwatering can lead to weak stems and fewer blooms. 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.