Bearded irises are a favorite spring blooming plant for many gardeners throughout the Central Valley. Irises are long-lived and easy to grow, they may become overgrown in time, requiring division and replanting. While looking through my files for information on this topic, I came across an excellent article written by Gay Wilhelm in the Summer 1995 issue of the newsletter, "The Curious Gardener." The following is an excerpt from that article.

Bearded irises are rhizomatous plants that are easily divided in late summer. Division is the process of lifting a clump of plants from the ground, pulling or cutting it into separate pieces, then replanting each piece in freshly prepared soil. To keep irises happy, a division should be made every three years. A good rule of thumb is to divide if you can count seven fans (groups of leaves) in a clump.

First, lift the clump with a garden fork. Brush away the soil to expose the old main rhizome and the younger ones coming from it. Choose side growths that have two or three strong buds or vigorous young shoots, as well as healthy roots. Any rhizome 2 to 3 inches long is suitable for replanting. Cut the rhizomes with a sharp knife, or break them apart. Discard the old rhizome, as well as any decayed parts or dead leaves. Trim the fan to 6 inches, trim the roots, then let the cut ends heal for several hours to a day before replanting.

When replanting remember that growth will occur outward from the end of the rhizome with the leaves. So when planting, point that end in the direction you want it to take. On slopes, set rhizomes with their growing ends facing uphill. Plant in full sun or light shade. Space the rhizomes 1 to 2 feet apart, spreading their roots well and covering with just enough soil to touch the bottom of the leaves. Irises like good drainage, but also do well in less than ideal soils.

Root rot diseases may kill plants if you overwater or plant the rhizomes too deep. And in spring, snails may chew the leaves. But all in all, irises are carefree, asking for a little water and fertilizer now and then. In return, their spectacular range of colorful blooms is a sight to behold.