Of a genus with about 300 species, iris perennials are distinctive additions to many styles of garden. There are three basic types of iris: bearded (or German), Japanese, and Siberian. Bearded iris have blooms with three upright petals and three that fall. Japanese and Siberian iris both have a flatter, but still distinctively outwardly curved, bloom. Except for the dwarf variety, iris stand from 24 to 40 inches tall with wide, sword-like foliage.

Most iris perennials prefer full sun, but will cope well enough with dappled light so long as it is ample. Iris are water lovers, meaning they thrive on moist but well drained soil. Several varieties, in fact, can be planted directly in water. These include the European Wild Flag (I. pseudacorus), a yellow bearded iris, and the Blue Flag (I. versicolor), both of which also do well in ordinary garden soil. Siberian iris will grow near water but not in it.

Iris are not especially suited to especially hot, humid areas. Pests and diseases that may afflict iris perennials include slugs, snails, bacterial soft rot (which affects the rhizomes), and leaf spot. Deadheading is essential. Dividing masses of iris is recommended--always in high summer--and encourages flowering.

Several Popular Iris Perennials

Hells Fire is a particularly commanding bearded iris with a dark red to maroon flower. Iris Batik is a medium tall bearded iris with an interesting boldly variegated white and purple flower. An especially attractive yet delicate Siberian iris is the Butter and Sugar, which at maturity stands about 28 inches tall with creamy yellow flowers and deep green foliage.