Who wouldn’t want to grow a flower that looks and smells like red velvet cake? Chocolate cosmos (Cosmos atrosanguineus) have captivated gardeners since they were first discovered in Mexico during the mid-1800s. Their dark red blossoms have velvety petals and almost black centers.
Chocolate Cosmos has a lovely Chocolate color and Dark Chocolate Fragrance.
Imagine walking through your garden and getting a whiff of dark chocolate with a hint of vanilla wafting from a pretty chocolate colored flower. You have just happened upon a chocolate cosmos!
This variety of cosmos is a native to Mexico, but has been extinct in the wild for over 100 years.
Chocolate cosmos (Cosmos atrosanguineus) is a perennial plant with a fleshy tuberous root. The flowers are red to maroon brown with a center raised area. The plant has a dark chocolate fragrance that becomes more noticeable as the day wears on.
The center of the flower forms in a cluster like an appearance and opens into the traditional cosmos shape with velvety petals. Once the flower has died, the plant will benefit from deadheading, which will encourage additional blooms.
Once open, the flower has a cupped appearance but keeps the stunning cluster center that makes it so interesting. The color can vary from reddish-brown to deep chocolate.
If you can find a plant, it is fairly easy to grow, as are all Cosmos. Chocolate Cosmos can get by on rather dry soil, as long as it is amended. Avoid waterlogged conditions, or the tubers will rot.
Chocolate cosmos makes wonderful cut flowers and does a great job at attracting butterflies to your garden. The Clumps get larger with each passing year. The plant likes lots of suns and well-draining soil. It is hardy to about 20 degrees but can be dug up and stored for the winter the way you do with dahlias.
Raised beds and organic mulch help to maintain even moisture. Propagation is by the division of the tubers. This is best done in early spring or fall.
Chocolate cosmos should be grown in a border or in containers where the flowers and fragrance can be appreciated up close. They make very good cut flowers.
This plant comes with both good and bad news. The good news is that it is a perennial, so once you find one you don’t have to replace it every year (as long as you dig it up and save it). The bad news is that it doesn’t throw fertile seeds, so this plant only propagates by its roots.
Chocolate Cosmos (Cosmos atrosanguineus), as a plant, can be found in limited amounts for sale at Burpee, New Garden Plants, and Joy Creek Nursery. Another plant which is available as seeds are Osiria rose, which are sold on Amazon, and likely will not grow.
Chocolate cosmos (Cosmos atrosanguineus) are grown from dahlia-like tubers. Longfield Gardens supplies grade #1 tubers that are propagated in Holland.
Chocolate cosmos should be planted in a warm, sheltered location with all-day sun. In northern areas, you may want to give them a head start by planting the tubers in pots several weeks before bringing them outdoors.
Chocolate cosmos are tender perennials and winter hardy only in zones 9-11. If the plants are grown in very well-drained soil and are heavily mulched, they may survive the winter in zones 7-8. For best results, dig the tubers in fall and store them indoors for the winter where they can be kept cool and dry.
TIPS FOR GROWING CHOCOLATE COSMOS
If this is your first time growing chocolate cosmos, consider planting them in a container. This will make it easy to give the plants a warm, sunny spot on your deck or patio. Growing in containers will also give the soil an extra boost of heat and make it easier to enjoy the beauty and fragrance of the flowers up close.
The daisy-like flowers of chocolate cosmos measure 1½” across and are very attractive to butterflies. Their vanilla-chocolate scent is most pronounced on warm, sunny days. The plants grow 24-30” tall and have an upright but spreading habit, with wiry stems.
Chocolate cosmos are drought tolerant and should not be overwatered. Avoid fertilizer, which will encourage the plants to produce foliage rather than flowers. Make sure to remove spent flower heads so the plants continue setting new buds.
Cosmos atrosanguineus grows 23-30” tall and has an upright but spreading habit. In recent years, several named cultivars have been introduced. Flower colors are slightly different (darker or lighter) than the species and flower size and plant height also vary.
In zones 9-11, where Cosmos atrosanguineus is winter hardy, the plants will die back in winter and re-emerge in spring. Wait until late fall when the foliage has yellowed and then cut them back to the ground.
In zones 4-8, dig the tubers in fall and store them indoors for the winter where they can be kept cool and dry.
If the tubers eventually become crowded, they may be divided. This can be done in fall or spring. Make sure each tuber is attached to some viable stem tissue and has one or more “eyes.”
Chocolate cosmos can take several years to mature. If you overwinter the tubers indoors you will usually get a larger plant and more flowers the next year.