They are excellent plants for perennial beds and borders. Bearded irises are hardy in USDA Hardiness Zones 3 to 10. While bearded irises are widely grown, they are not trouble-free. Bearded irises quickly become overcrowded, resulting in fewer flowers. Clumps should be divided every 3 to 4 years.
Several pests are problems on bearded irises.
The most destructive pest is the iris borer. The iris borer larva tunnels into and devours much of the rhizome. Various leaf spots can disfigure the foliage. They are available in shades of blue, purple, wine-red, pink, white and yellow. Siberian irises bloom in late May or June.