By: Garden Gate staff
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Dead center? Time to divide
That cluster of dead rhizomes in the center of this Siberian iris takes up space and won’t let new growth sprout. Your best bet is to lift the entire clump. With a spade, loosen the root ball all the way around the outside, then lift it free of the ground. Do this in early spring, when the foliage is still small so you can see what you’re doing.
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Slice it into smaller pieces
With the clump out of the ground, use your spade to slice it into four to six sections, as if you’re cutting a pie. With a soil knife or small saw, cut off the dead “tip” of each wedge and discard it. Cut the dead rhizomes off each chunk and discard them, too.
One thing to keep in mind: If the clump is too big for you to lift out whole, just cut the clump into wedge-shaped chunks and take them out one at a time.
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Replant the healthiest parts
Of course, you could divide these clumps down to much smaller pieces, but you’ll get a lot more impact if you replant a chunk about the size of the one in the photo, which is roughly 6 inches across. Try not to disturb the roots on the clumps you’re going to replant. Plant it at the same level it was growing before, and keep it well watered the first year.
By the way, this technique works for lots of other perennials, too, including asters, Shasta daisies and sneezeweed.