Answer: Iris are traditionally divided during the summer after they have bloomed, in part because dividing them in early spring could prevent them from blooming this spring. To do it, trim back the foliage and then simply lift the clumps (a garden fork workd nicely) and separate them. Some sections will simply fall apart and that is okay.Throw away anything that is soft or mushy or has borers in it. Throw away the oldest parts and save the vigorous outer growth for replanting. If you want to make smaller pieces, simply cut them with a knife and allow them to callous for a day or two before replanting. It is easier to do than to describe. When you replant, make sure you do not plant them too deeply.
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