I clearly remember planting the strangely-shaped cosmos seeds among my irises one spring about 5 years ago. My neighbor behind me said something like, "oh, well, you'll never have to plant them again." So true! I do have to do a fair share of pulling them out of areas where I don't want them. Cosmos are good cutting flowers and butterflies like them. They bloom when the irises are long-gone, and the leaves are starting to look ragged and faded. And the biggest bonus - goldfinches love Cosmos seeds. Even when you don't see goldfinches, their chirping and singing is a delight to hear.