Answer: When the flowers are spent, cut off the flower stem but leave the foliage alone. The leaves will die down with the first frost. Irises should be divided every 3-4 years, or when flowering slows which indicates they are overcrowded. Late summer or early fall is a good time to dig and divide iris. Dig up the clumps with a garden spade and separate the rhizomes. Then break away the ends of the rhizome and replant them, discarding the old center of the rhizome. Before replanting you can cut the fan of foliage down to 4" or more (for ease in handling). Dig a shallow trench and lay each rhizome in the trench, spaced about 6" apart, with the ends pointing in the direction you want new growth. Cover with an inch or two of soil and water the bed well. Next spring your renovated iris bed should bloom with great enthusiasm!
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