Thanks for writing. The best time to transplant tall bearded iris is in early to midsummer.
There are tons of good plants that do great with iris...some of my favorites include phlox, perennial geranium, coneflower, lamb's ears, baptisia, and amsonia. Learn about these or do a search for more with our online Plant Guide! http://www.bhg.com/gardening/plant-dictionary/
---Justin, Senior Garden Editor, BHG.com