Marietta Daisies Garden Club

Dividing Bearded Iris

Bearded irises are one of the showiest flowers in the spring garden, and they are also one of the easiest to propagate and transplant.

Bearded Iris Anatomy

Bearded irises grow from fleshy underground stems known as rhizomes; plants that grow from rhizomes often survive poor growing seasons because the rhizomes store starches and proteins.

Rhizomes also enable the asexual propagation of plants: Cut off part of a rhizome, replant it, and you will soon have a plant identical to the parent.

As iris rhizomes spread, they can become crowded. This stresses the plants and may even cause them to stop blooming and become susceptible to pests like iris borers.

Why and When to Divide and Transplant Bearded Iris

• Iris roots become woody and overgrown over time unless the clumps are lifted, divided, and replanted every three to four years.

• Overgrown clumps tend to get barren in the center, with foliage and flower stems that appear only around the outside of the clump.

• Don't try dividing while a bearded iris is in bloom.

• Instead, the American Iris Society recommends that you lift, divide, and transplant any time in mid- to late summer after the foliage begins to decline following the spring bloom. Transplanting during this time, when the weather is relatively dry, minimizes the chances for fungal disease but still allows enough time for the rhizomes to be established well before winter sets in.

• By dividing and transplanting your irises, you will rejuvenate the plants and be rewarded with a greater number of healthy blooms in the spring.