Well, you will typically not get as many blooms the year after a division, that is kind of normal, just because there are few growing points per plant and you only get 1-2 stems of flowers per growing point (leaf fan). I dont' know if your problem is just that, or more serious?
When are you dividing them? They want to be done about 4-6 wks after flowering, for typical bearded irises. (Or 4-6 wks after the first flowering of the year, for rebloomers).
Are they blooming well for you BEFORE you divide them, or are they simply not doing well for you at all in that site? I wonder whether you may be burying them a bit too deep (I've always planted irises so that the top half of the rhizome is exposed above the soil, although that may be different in different areas/soils I suppose), or if they are getting too much shade or have issues with your soil?
When you say you are leaving 'about five leaves', how many separate growing points are you leaving? I've had best luck giving each division 2 growing points (fans). (e.t.a. - I know other people sometimes have success with dividing into just-fan pieces, but when I do that they often sulk). Point them so that future growth (which proceeds horizontally over the surface of the ground) is going to go in the direction you want the plant to expand.
Just trying to cover all the bases, do any of those ring any bells?, good luck, have fun,
Pat
Don't worry about them--just plant them where you want them to be, and sooner or later they'll fill in and bloom like they look "in your mind's eye." I moved some to a corner of the yard that needed some color. I'll probably see some nice blooms there from them NEXT year.
