Summer/fall bloomFrost tender.
Sow seeds 1/2 inch deep, 1 to 2 inches apart in a sunny location in well-worked garden soil once danger of frost is past. Keep seed bed evenly moist but not soggy. Seedlings emerge in 5 to 10 days. Keep well weeded and watered while plants are young; mature cosmos can handle hot and dry conditions.
Sow seeds 1 inch apart in a container of seed starting mix, 4 to 6 weeks before last expected frost. Cover 1/4 inch deep, keep moist and provide a good light source. Plant outdoors once weather warms up after gradually acclimating seedlings to outdoor conditions.
Space 6 inches apart when seedlings are large enough to handle.
Carefree cosmos are among the easiest and most reliable of all summer flowers. Plant well-bred kneehigh Sonata for quick bloom and manageable size. The bright silky flowers and ferny foliage combine beautifully with blue salvia, dwarf sunflowers and zinnias. Cutting Sonata’s vibrant flowers for bouquets actually prolongs the blooming season.