The annual forms (Cosmos bipinnatus and C. sulphureus) are half-hardy, which means their seeds must be sown under cover before risk of frost has passed. Having just one year to set seed ...

Flowers from this species grow to be 4 to 7 feet tall. Cosmos bipinnatus: A mix of purple, pink, and white flowers, the blooms of C. bipinnatus range from 1 to 6 feet in height. Cosmos ...