Cosmos problems

It covers garden cosmos, Cosmos bipinnatus, the common lacy-leaved annual. Cosmos is a genus with other species, including sulphur cosmos and chocolate cosmos, so check the botanical name on the plant or seed packet.

Plant it in full sun for the strongest flowering. NC State Extension recommends at least a half-day of direct sunlight; partial shade is tolerated, but deep shade is a poor fit.

Sow outdoors after frost danger has passed and the soil has warmed. Keep the seedbed moist as the seeds germinate; seedlings can also be started indoors and moved outside after the weather is safe.

Use freely draining, average to lean soil. University of Illinois Extension recommends low-fertility soil and full sun; avoid keeping the roots saturated or feeding heavily.

Remove faded flowers to encourage more blooms. Tall cultivars may need support in exposed sites; leave a few flowerheads if you want the plant to self-seed or plan to collect seed.

Its exact-species status was not verified. ASPCA’s database returned no Cosmos listing and says the list is not all-inclusive, so do not assume this means the plant is safe. Prevent chewing and contact a veterinarian about an ingestion.

Keep the seedbed evenly moist until germination and water young plants while they establish. Mature Cosmos bipinnatus tolerates some dry soil; water at the base during a prolonged dry spell, then let excess moisture drain. Avoid keeping the roots continuously wet. In practice, water check rainfall and the soil rather than following a fixed calendar. Give seedlings and recently transplanted starts regular moisture; established plants usually need extra water only when dry weather persists. Check the root zone below the surface. Water when it is dry during an extended rain-free period, and make sure the bed or pot drains freely. Sow after frost danger has passed and keep the soil moist while seeds germinate. Once plants are established, reduce supplemental watering when regular rain keeps the soil from drying out.