Cosmos are some of the easiest flowers from which to save seed.We harvest and save cosmos seeds after every growing season, and plant them out again the following spring.
Cosmos seeds are located in the centre disc of the flower. Seeds will form on the flower if pollinators fertilize the tiny florets growing within the bloom.
Harvest cosmos seed at the end of the growing season, when the seed heads have matured, and the seeds become loose and begin to fall away from the pods.