James H. Schutte
Family
Asteraceae
Botanical Name
Cosmos
Plant Common Name
Cosmos
General Description
Most know Cosmos for the two common garden-grown bedding annuals, common cosmos (Cosmos bipinnatus) and sulphur cosmos (Cosmus sulphureus), which offer lots of colorful daisies in summer. But this genus has approximately 25 species of annuals and herbaceous perennials, most uncultivated. They are naturally found in the meadows and scrub of subtropical and tropical regions across the Americas, particularly in Mexico.
Cosmos species tend to have bushy habits; most are upright or spreading and well-branched. The leaves are held in opposite pairs and may be simple (without divisions), lobed or deeply dissected with an almost feather-like appearance. Leaf and stem surfaces tend to be smooth but some species are hairy or fuzzy.
Most are warm season plants that bloom in summer or fall in the United States. Their showy daisies may be single or produced in loose clusters on leafy, branched stems above the foliage. The flowers typically have yellow eyes, or disk centers, surrounded by a ring of showy ray petals, which may be white, red, pink, purple, yellow or orange. Bees, butterflies and other insects pollinate the blooms, and the seedheads that follow are filled with small, flattened, black or brown seeds with hooked hairs that can catch on clothing or fur.
Adaptability and easy cultivation are two general hallmarks of Cosmos. Most prefer sunny sites with average to fertile, well-drained soil. Some are drought tolerant and all heat tolerant. Still, be sure to check specific cultural needs when growing any species for the first time. Taller types tend to require staking. Annual forms self-sow freely in the garden, so remove all seedheads if you don't want volunteers. Deadheading will extend the flowering period for some, but not all, Cosmos. Popular cultivated forms are great for annual beds, cutting and wildflower gardens.
