Irises, those tall and elegant garden standards are among the easiest to grow of all our flowers in the garden beds. One of the benefits of growing bearded iris (Iris spp.) is the ability to share them with friends or add them to other garden areas when you dig and divide them every few years. This keeps the iris performing and blooming at its peak. If left undivided, flowering decreases and the rhizome is subject to pests and damage from soft rot and borers. Large, showy flowers appear from early spring into summer, depending on the cultivar, in all colors and color combinations, giving iris the name of rainbow flower. Bearded iris grow in U.S. Department of Agriculture plant hardiness zones 3 through 10.