Cosmos (Cosmos spp.) is a moderate reseeder, which means that it drops plenty of seeds to bring it back year after year without becoming an uncontrollable nuisance. For cosmos to reseed itself, you have to leave the faded flowers in place long enough for seeds to form.

Will cosmos come back every year?

Cosmos are annuals meaning they do not come back every year. In order to have blooms every year, you will need to resow your seeds the following spring. The only difference, however, is Chocolate cosmos (also known as cosmos atrosanguineus) which is grown from like a dahlia from a tuber.

Can cosmos survive winter?

They are not hardy and if you leave them in your borders over winter there is a real chance they will be killed by a sharp frost, or rot in cold wet soil.