Irises are beautiful, showy plants that can be an attractive addition to almost any garden. They come in several different types, from the commonly known bearded iris to the crested dwarf iris that is native to parts of the Southeast United States. Even the bearded iris comes in several different varieties, and new hybrids are being added all the time.
The bearded iris is the type of iris most people grow in their gardens. It is grown from rhizomes, or swollen root stems. This iris grows in three different sizes: dwarf, intermediate, and tall. The tall bearded irises grow from two to four feet. The dwarf irises may be as small as six inches. The tall irises are the most common type grown, although the others also have their places in the landscape, depending upon the effect you wish to make.
The bearded iris will grow in most of the United States. It blooms in the late spring to early summer. Some varieties will bloom a second time, in late summer. Bearded irises prefer to grow in neutral, well-drained soil in full sunlight. Some varieties will tolerate drought, but most prefer regular watering.
Plant the rhizomes in June or July. Before you plant the rhizomes, dig compost into each place where you will plant them to a depth of 10 to 12 inches. Plant them one foot apart under one inch of earth. Do not bury them too deeply. If your soil is heavy clay, you may leave the rhizome slightly exposed. Water thoroughly.
Never use high nitrogen fertilizer on the irises, as this will cause lush leaf growth that may attract pests such as the iris borer. It will also cause the irises to bloom less abundantly than they otherwise would. Do not water the irises too much; they should dry out slightly between waterings. During blooming season, keep spent flowers picked.
Cut the flower stalk down to half its height once the plant has finished blooming. Never cut it too close to the rhizome, as that may cause the rhizome to rot. The leaves of the iris will start wilting once-blooming season is over. Remove them after they have wilted. The next spring give the rhizomes a heavy feeding of bone meal.
Divide the irises every four or five years so that they do not get too crowded. Overcrowding may lead to disease and weakened plants. Divide the plants after they have bloomed. Carefully dig up each plant with a small shovel. Break each plant into smaller clumps of rhizomes. Inspect each clump carefully for rot or borer damage.
Cutaway the damaged parts, and discard any rhizomes that are not healthy. Keep the rhizomes moist while you prepare the soil for them. Prepare each planting spot as before. Dust the parts of the rhizomes where they were cut with a little bone meal, and plant shallowly.
The Siberian irises is a type of beardless iris that is becoming more easily found in nurseries. They bloom in early summer and the flowers last for a long time. They will grow about three feet tall. The care for Siberian irises is much the same as that for bearded irises.
The soil requirements are different, as the Siberian iris likes a damp, acidic soil and will tolerate more shade than bearded irises. The Siberian iris is a good choice for a semi-bog garden or a place at the side of a small pond.
Crested dwarf irises grow in many deciduous woodland areas in the United States. At their tallest, they are only nine inches tall. They have a single two to three-inch-wide violet-blue flower on top of each flower stalk. These irises may be obtained from some plant nurseries that specialize in woodland plants.
They tolerate much more shade than either the bearded or Siberian iris, preferring the dappled shade found under tall trees. They like well-drained soil, but not one that is too dry. As with the other irises, do not plant them too deep.
They will grow well at the edge of a wooded area or rock garden. Once naturalized in your garden, they will require little care.