Chocolate cosmos, or cosmos atrosanguineus, is a tender perennial that has blooms that have the fragrance of chocolate. Although chocolate cosmos has the scent of chocolate, the plant and flowers should not be eaten. The flowers' colors range from a brownish-red to a maroon, contrasting with the plant’s deep green leaves. This plant is in the same family as daisies and sunflowers.
Cosmos atrosanguineus has an unusual background. Native to Mexico, chocolate cosmos no longer grows in the wild and is considered to be extinct. This plant is sterile and does not produce seeds. All of the chocolate cosmos plants in existence today are derived from a single plant that lived in 1902. The plant continues to exist through splitting and planting the tuberous roots of cosmos atrosanguineus.
During the first year after planting, chocolate cosmos should be watered frequently to help establish the plant's root system. When the weather is hot, cosmos atrosanguineus may need watering more than once a week. Overall, the soil should be moist all of the time, but not drenched. Chocolate cosmos thrives when planted in full sun.
Cosmos atrosanguineus is susceptible to cold weather. In areas that experience frost and colder weather, the plant should be dug up before the first frost and stored. Chocolate cosmos can be trimmed back during the fall in more temperate areas.
This type of cosmos should be planted about 24 to 36 inches (60 to 90 cm) apart. Chocolate cosmos will grow to be about 18 to 24 inches (45 to 60 cm) tall. Under the right conditions, chocolate cosmos will bloom almost all of the year except during mid-winter through early spring. The plant can be divided in the spring. It takes two to five years for a plant to mature.
Chocolate cosmos can attract beneficial insects into the garden. Its flowers can attract bees. In addition, cosmos atrosanguineus can bring butterflies into a yard, along with other insects that feed on nectar.
Interested gardeners can plant a chocolate-based garden. "Chocolate plants" in addition to cosmos atrosanguineus include the yellow chocolate daisy, which also has a chocolate scent; the shrub diablo ninebark with its chocolate-colored leaves; and purple fountain grass. Other choices include the dark red colored black sunflower, the edible chocolate mint, and the chocolate cherry tomato. The chocolate cherry tomato is also edible and tastes like a "regular" cherry tomato.