Cosmos Seeds,
Bright Lights

Plant Bright Lights cosmos after the last frost, when soil temperatures reach at least 60 F. In cooler climates, seeds can also be started indoors 3-4 weeks before the last frost and transplanted once the weather has warmed. In warmer regions, cosmos can be grown nearly year-round. Blooms typically appear 60-90 days after sowing and last until the first frost. To find the best planting time, check the last frost date for your area. Learn more about frost dates by checking out our blog post, 'Our Experts Answer Questions, Share Resources.'

Sow seeds directly in the garden after the danger of frost has passed. Lightly press the seeds into the soil at a depth of 1/8-1/4 inch, 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 during germination. If starting indoors, choose a light, well-draining seed-starting mix. Transplant seedlings outdoors only after the risk of frost has passed, being careful not to disturb the roots.

Avoid excessive fertilization, as it encourages leaf growth at the expense of flowers. Once established, cosmos are drought tolerant and need minimal watering. Taller plants may need staking in windy areas. Keep plants deadheaded to prolong blooming. 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.