Cosmos will flower all summer until the first heavy frost. Can be started indoors 3/25-4/21 or sown directly outdoors after frost (5/20-7/20). Plant seeds 1/4 - 1/2 ” deep, with final spacing 12” apart. 7 -10 days until germination at 75°F.
For long lasting cut flowers, snip stem when petals begin opening but before they have opened completely.
Cosmos are an easy seed saving crop, and may reseed in the garden. Collect seeds by hand once they have turned brown and when they are dry. Clean by winnowing. This cosmos is a different species than (and will not cross with) the pink/white cosmos types. Cosmos is insect pollinated, so plants can be crossed by bees within 1/4 mile but all orange cosmos are similar so home gardeners don't need to worry about isolation distance. Collect seeds from as many plants as possible to preserve genetic diversity.