Cosmos atrosanguineus is also known as the chocolate cosmos. The stunning dark-brown colored flowers actually do smell like chocolate! Cosmos atrosanguineus is a lovely border plant that is easy to propagate from root cuttings. Because it is a tropical plant native to Mexico, this plant is not winter hardy. Therefore, It is best to dig up the rhizomes and let them overwinter in peat during the winter. They can be planted out in May.