Cosmos is an easy-to-grow flower that can reseed itself and grow in hot, dry conditions, making it a good choice for North Carolina gardens. The hardy annuals will give you blooms from summer to frost.
Plant cosmos in a location that receives at least a half-day of direct sunlight. Sow the seeds outdoors after the danger of frost is past and when the soil has warmed to at least 65 degrees. Rake seeds into a loose soil. Planting seeds too deeply will hinder germination. Keep the soil moist for 5 to 10 days after seeding. Seeds will germinate in 7 to 21 days. Cosmos needs only basic care to provide an abundance of colorful blooms all summer. Taller varieties may need staking if subjected to high winds and frequent storms.
Be cautious not to overwater your plants. That and over-fertilizing can lead to the plant producing fewer flowers.
When the spring-planted cosmos appears to have an abundance of dried seed, do not remove the plants. Encourage re-bloom by cutting the plants back to 12 to 18 inches high. They will be back in bloom in a month and the seed that is cut off will fall to the ground, germinate in the hot soil, and increase the density of your plant population and the eventual bloom display.
Insects, Diseases, and Other Plant Problems:Issues effecting this plant include aphids, gray mold, stem canker and powdery mildew. Allowing good airflow will help avoid diseases.
