Purple Cosmos Flowers
(Image credit: art Photo)

Cosmos plants (Cosmos bipinnatus) are an essential for many summer gardens, reaching varying heights in many colors, adding frilly texture to the flower bed. Growing cosmos is simple and cosmos flower care is easy as well as rewarding when single or double blooms appear on stems reaching 1 to 4 feet (0.5-1 m.). 

Cosmos plants may be featured at the back of a descending garden or in the middle of an island garden. Taller varieties may need staking if not planted in an area protected from the wind. Planting cosmos flowers results in many uses of the specimen, such as cut flowers for the indoor display and backgrounds for other plants. Cosmos can even be used as screens to hide unsightly elements in the landscape.

How to Grow Cosmos Flowers

When planting cosmos flowers, locate them in soil that has not been heavily amended. Hot dry conditions, along with poor to average soil, are optimum conditions for growing cosmos. Cosmos plants are usually grown from seed. Scatter seeds of the cosmos onto a bare area in the location where you wish to have growing cosmos. 

Once planted, this annual flower self-seeds and will provide more cosmos flowers in the area for years to come. Daisy-like flowers of the cosmos plant appear atop tall stems with lacy foliage. Cosmos flower care can include the deadheading of flowers as they appear. This practice forces growth lower on the flower stem and results in a stronger plant with more flowers. Cosmos flower care can include cutting flowers for indoor use, achieving the same effect on the growing cosmos plant.

Varieties of Cosmos

More than 20 varieties of cosmos plants exist, both annual and perennial varieties. Two annual varieties of cosmos plants are primarily grown in the U.S. Cosmos bipinnatus, called the Mexican aster and Cosmos sulphureus, or yellow cosmos. Yellow cosmos is somewhat shorter and more compact than the commonly used Mexican aster. 

Another interesting variety is Cosmos atrosanguineus, the chocolate cosmos. If there are no cosmos to self-seed in your flower bed, get some started this year. Direct sow this frilly flower into a bare area of the bed that will benefit from tall, colorful, easy care blooms.

Becca Badgett

Becca Badgett was a regular contributor to Gardening Know How for ten years. Co-author of the book How to Grow an EMERGENCY Garden, Becca specializes in succulent and cactus gardening.