Dividing iris every three to five years will keep your iris bed healthy and looking well-groomed.
Three simple steps are all you need to know and do to divide and/or transplant your iris:
Remove the new healthy growth from the outside of the bulb/rhizome and throw away the original older middle portion of the bulb.
Using scissors or your pruners, trim the leaves down to about 6 inches and replant the bulb being sure to keep the foliage upright
Remember also to keep in mind the important parts of planting iris bulbs as you divide and transplant your iris:
You'll probably find that you have lots of extra iris after dividing them and transplanting them. Be sure to share the extras with neighbors or other gardening friends!