Answer: You can leave the foliage on irises until it withers naturally in the fall or winter months. The leaves manufacture food for the rhizomes so if you cut the leaves back, the plant won't be able to store needed energy for next year's growth and bloom. If your irises need dividing, you can dig and divide in August. Roots and leaves can be trimmed back to about 6 inches prior to transplanting, to make the transition a little easier on the plants. Otherwise just let the foliage yellow and die naturally.
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