Who wouldn’t want to grow a flower that smells like chocolate cake? Chocolate Cosmos, Cosmos atrosanguineus, has velvety, burgundy-maroon flowers so named because of their sweet, cocoa-like fragrance. The fragrance is due to vanillin, an organic compound also found in cocoa and is most noticeable on warm and sunny days. The flowers are similar to garden cosmos, Cosmos bipinnatus, but the flowers tend to be smaller, but more numerous.
This heat-loving plant from Mexico is a tuberous perennial, that grows best in a warm, sunny location, where they’ll bloom from midsummer to fall.
Similar to garden variety cosmos flowers, but a bit smaller, this perennial is only hardy to zone 9, so here in Maryland, I grow it as an annual and have to dig up the fleshy tuberous roots in the fall and store with my dahlia tubers. I winter over all my tubers in a greenhouse that doesn’t freeze during the winter and keep them cool and dry.
Grown from tubers or seeds, you can get a head start with a tuber.
Chocolate Cosmos Care
- Grow in full sun (at least 6 hours) in well-drained soil
- Water deeply once a week and let the soil dry between waterings
- Avoid temps below 50 degree Fahrenheit so they are very frost sensitive
- Fertilize sparingly in the spring for good growth all summer but too much fertilizer can encourage more foliage than flowers
- Tolerant of high humidity
- Dig up the fleshy tubers if you live in a colder climate than zone 9 and save them in a dry dark space over winter
- Can be started from seed in the spring
- Pinch young plants to produce side branching to make a more vigorous plant
- Sheer back the entire plant after the first round of flowering and they will spring back with new growth and flowers
- You can propagate the roots similar to dahlias by digging up the fleshy root, removing the soil and cut it into sections so that each section has 2 ‘eyes’ or growth buds
- Plant the roots about 1 inch deep when all danger of frost is gone
There are several cultivars of Chocolate Cosmos that have been introduced:
- Pinot Noir was released in New Zealand and has small flowers
- Choca Mocha is a dwarf variety about 12 inches tall
- Black Magic is another compact selection growing 12-24 inches tall and the flowers are almost black
You can buy the roots or seeds at Burpee.
