Best of the bunch
●● Cosmos Atrosanguineus
Best known as the chocolate cosmos, because it produces masses of burgundy flowers which smell like chocolate, this Mexican perennial with green, deeply lobed leaves, flowers continuously from midsummer to early autumn if you deadhead it regularly and feed it occasionally.
The flowers are like small, single dahlias.
It’s not completely hardy, but should survive most winters if covered with a thick layer of mulch.
If you live in a really cold area, dig up the tubers in autumn and store them in trays of compost in the winter, which you need to keep slightly moist.
Plant the cosmos out again in full sun in moist or well-drained soil after the last frosts of spring.