Tall Bearded Iris: Iris like a sunny well drained area. Plant the rhizomes just below the surface of the soil, so that when watered the top of the rhizome is exposed. Plant too deep and you won’t have many flowers and may kill the iris. Water until a new leaf appears. Overwatering can cause root rot. Fertilize with bone meal or a low nitrogen fertilizer such as 6-12-12 at planting and again in the spring and a month after blooming. Separate every 4-5 years during the months of July, August and September.
Japanese iris: The largest flowers of all iris, with lovely forms, colors and patterns, they require full sun, a rich, acidic soil and ample water. Mulch will help hold in water and reduce weeds. Japanese iris are heavy feeders and an azalea-type fertilizer in the spring, just after bloom, is best. Keep the pH between 5.0 and 6.5. Japanese are generally prodigious growers so allow three or four feet between plants
Siberian Iris Culture: Siberian iris culture is similar to that of japanese Irises. They are among the easiest perennial plants to grow, but until they are well established they must be kept moist. If the roots are dry on arrival, soak them in water for several hours or overnight before planting. Plant where they will receive full sun light for at least half a day. Plant with the top of the rhizome 1 to 2 inches below the surface. It is a good idea to place the rhizome on a mound of dirt in the hole dug for it to insure that there is not an air pocket beneath it. The roots should be spread downward over mound and then replace the soil, and water well. Each spring a small handful per plant of ordinary (10/10/10) commercial or organic fertilizer may be used. An acidic fertilizer such as Miracid is recommended as a foliar drench for weak plants. DO NOT use lime around siberian irises.
Louisiana: Louisiana iris like conditions much like Siberian Iris. They are a good plant for water or bog gardens.
For more information on dividing and transplanting iris, check out my July 28 post in the July 2010 archives.