Answer: It would be better for your irises if you dig, divide and then replant them immediately rather than trying to store them for replanting in the spring. If you cannot replant them in the same bed, plant them in containers and leave the containers in your garden over the winter months, then replant in the spring.
To dig iris, use a spade or garden fork and gently lift them up. Once out of the ground you'll discover that the center of the rhizomes are usually dead but new growth is coming from the ends of the rhizomes. Break off the live parts and discard the center. Replant the rhizomes just an inch or two beneath the soil surface and be sure to space them 8-10" apart so they'll have room to grow.
Best wishes with your irises.
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