Dahlias are one of the most versatile bulbs for the summer garden. Dwarf types reach only a few inches tall; the monster "dinnerplate" varieties grow more than 6 feet (and feature flowers bigger than your head). Dahlia blooms come in nearly every color of the rainbow and a range of flower forms - from daisy-like singles to more alienesque quilled types.
How to Grow Them: Dahlias appreciate a spot with full sun and moist but well-drained soil. Stake taller varieties to protect them from the wind. Dahlias are hardy in Zones 8-10; in colder climates, dig the tubers and store them a frost-free place for winter. Or treat them as an annual.