Why aren't my iris blooming?
If your irises have been in the same location for several years, they may be overcrowded and in need of division. Bearded iris, usually need to be divided every 3-4 years. Lift and separate plants in late summer. The spongy rhizome may be a sign of iris borer. This serious pest of bearded iris overwinters as an egg attached to the leaves. The borers hatch in mid-spring and chew their way down to the rhizome. Once in the rhizome, they continue to feed, hollowing out the insides. Foliage may yellow from injury to the rhizomes. Larvae crawl out of the rhizome in late summer to pupate. Moths hatch in early autumn and lay eggs on iris foliage and nearby garden debris. To control iris borer, clean up and destroy garden debris around irises in late fall or early spring before the eggs hatch. If you find borers in rhizomes, dig up the plants, remove the borers, destroy badly damaged sections, and replant healthy ones. You can also spray affected plants in spring with an insecticide labeled for iris borer.
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