There over 200 varieties of plant in the iris family, and so many colors of blooms that the Greeks named the flower after the goddess of the rainbow. All species have characteristic flat, sword-shaped leaves. Their springtime blooming habits combined with their height makes them a good backdrop for low-growing summer blossoms. Some of the most striking Iris are tall varieties that can reach well over 3 feet in height.
Tall Bearded Iris
The bearded iris is a hybrid of a German species that is commonly planted due to the ease with which they propagate and grow. The blooms on a tall bearded iris are extremely large, and may reach heights of 40 inches. Care of bearded irises is minimal. Plants are drought tolerant and prefer full sun. They should be planted in just a few inches of soil in late summer or fall well before the first frost for your region. Irises prefer very little fertilizer, and too much nitrogen can cause rot. Irises bloom from the end of rhizomes, and the roots spread as they grow. The plants should be divided every three to five years to prevent overcrowding, and to encourage more blooms.
The Japanese iris has been known variously as butterfly iris and Kaempferi irises. They have been cultivated in Japan for over 500 years. Once these irises were only allowed to grow in royal gardens. The blooms are open, like a butterfly with spread wings. This is a sharp contrast to the cup-shaped design of bearded irises. Japanese irises prefer the same conditions as impatiens and ferns--moist soil and shade. However, they will tolerate full sun.
Some varieties of Louisiana iris can reach up to six feet in height. These irises are similar to appearance to Japanese irises in that they have open blossoms rather than the cup-shaped blossom of bearded irises. Though the Louisiana irises are planted less often than bearded irises, they can be grown across the United States and well into Canada. The plants prefer partial shade, but need at least six hours of sun to produce abundant blooms. The plant grows wild in the swamplands of Louisiana as well as ditches, bogs, along pond edges and anywhere there is fertile damp soil. In the garden, the soil should be slightly acidic and rhizomes should be mulched to hold in moisture and prevent sun scald on the roots.