They are only annuals,I collect the seed each year and grow new ones, they are really easy from seed and usually sprout within a few days, a lovely plant I wouldn't be without each year :-)

Hi, welcome to GoY, there are 25 species of Cosmos, the majority of which are annuals, C atrosanguineus, or common name chocolate plant, is a perennial, but is only frost hardy, Derek.

thanks so much. They are so beautiful I want to make sure of them next year. I'll take the advice and keep the seeds to sow.

If you like them then try Tree Dahlia (dahlia imperialis). If you live somewhere like California then they grow to 14ft tall and are covered in flowers.