Chocolate cosmos (Cosmos atrosanguinea) is both nose and eye candy for your garden. When it’s in full bloom, mature blossoms on long, slender stems look like candy kisses on a stick and fill the late afternoon with the sweet scent of vanilla tinged chocolate. New blossoms hug the foliage of the plant, nearly concealing it with their numbers! Add to that the sweet chocolate fragrance and you end up with something very special.
Although chocolate cosmos is endangered in the wild, transplants are easily found at most nurseries and garden centers in the spring. However, gardeners who are inexperienced in how to grow chocolate cosmos may overlook what seem to be small, messy tangles of miniature dahlia leaves, unaware that once established, prolific blossoms nearly conceal the foliage. Once in bloom, chocolate cosmos blossoms continuously throughout the summer into the first frosts of autumn.
If you’re planning a gothic garden, chocolate cosmos is the plant for you. Sometimes referred to as black cosmos, dark maroon blossoms are so deep in color that they appear brown/black in late afternoon and evening.
A native of Mexico, the chocolate cosmos is a half-hardy perennial and a sun loving plant that is moderately drought tolerant.
You’ll most easily grow chocolate cosmos from transplants purchased at your local garden center or nursery. Large clumps of established plants can also be divided to provide as many as three or four transplants.
Plant chocolate cosmos in organically rich, well-drained soil in a location that gets full sun. Keep the transplants moist until they established roots and you see the beginnings of some new growth.
In the fall, when foliage dies back, cut plants back to about two inches from the root and over-winter them in a frost-free area. Chocolate cosmos is hardy in zones 7-10. In these zones, you may opt to cover the plants with a cloche to protect them from danger of frost.