Answer: Overcrowding is the number one reason for non-blooming irises. If you are sure they will not bloom this year you can dig and divide them now. If there's a possibility that they will bloom, wait until the flowers are spent then cut the plants down by about two-thirds so they are easy to handle. Dig them by prying them up with a garden fork and breaking them into division, discarding the oldest parts where there are no leaves and replanting the plumpest parts of each rhizome. Plant just below the soil surface, water them in well and then cover over the plants with several inches of organic mulch. I'm sure they will bloom for you next year. Enjoy!
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