Confident color all summer long. Coreopsis is a garden favorite because it blooms from June to September in full sun, thriving in hot, dry conditions. They are rugged, dependable and flower profusely. Coreopsis does not require a lot of maintenence. For optimum flowering, however, deadheading after the first blooms fade is recommended. After a few years, the clump may need to be divided in early Spring to keep it from overcrowding.