Irises are showy, colorful flowers. Desirable for their hardy nature and long-lasting blooms, these plants come in a wide range of shapes, sizes and hues, from the cold-hardy Siberian iris to the distinctive and popular bearded iris. These flowers bloom in every color of the rainbow, according to Clemson University, making it easy for the home gardener to choose just the right species and cultivar for her garden.
The Siberian iris is desirable for its long, slender leaves that stay green all summer. The flowers are symmetrical, without the long, distinctive "beard" or "lip" that bearded irises have. These irises, which can tolerate freezing temperatures, grow in rhizome clumps and range in size from 1 to 3 feet. They root deeply and spread rapidly.
The crested iris is a small, or dwarf, plant that blooms at a height of only 6 inches, according to the University of Minnesota. The flowers appear to float on the leaves because the stems are so short. Iris cristata is also known for its ability to grow even in poor soils.
Iris Germanica "Florentine"
"Florentine" is a centuries-old cultivar of Iris germanica, according to Clemson University. This iris is a classic for its very pale blue flowers and its beautifully scented rhizome, which has been used in perfume-making.
The Japanese irises are a little pickier in their growth needs than many other species of iris. Still, the remarkable, large, heavily ruffled flowers, considered to be the best of all the irises, more than make up for the culture requirements of this flower. Japanese irises need very fertile, slightly acidic soil that is continually moist. Some cultivars will even grow in shallow water.
The Dutch iris is commonly forced in containers along with other spring-blooming bulbs, according to North Dakota State University. It is also cold hardy and will grow in poor soil. For that reason, it is often seen in rock gardens.