Answer: Iris may stop blooming if they've become overcrowded, if their leaves were cut back too early, or if they've been overfertilized. If your iris refuse to bloom this year, wait until August, then dig and divide them. Dig each clump, cut the roots and the fan of leaves to about six inches, then divide the rhizomes by cutting off both ends and discarding the old center. Iris rhizomes grow vertically and only the new growth will produce a flowering stem. After dividing the rhizomes, replant them in a freshly prepared bed into which you've worked several inches of organic matter. Plant so the rhizomes are barely covered with soil, then water them in well. By the following summer your iris should produce blooms.
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