HI
butterflylover_52 you might need to divide them. i do mine every three years.once a iris blooms the same
plant will never bloom again.but the new growth that they put on will.if you have never divided them they might be over crowded so no new root or rhizome system has room to develope.i would dig them up at least some of them so new roots can have room to grow and start new beds with ones you dig up so they can grow new rhizomes root systems on all of them. but don't
plant them to deep just enough soil to cover the roots or rhizomes.here a link that tell you a lot about them.
http://www.thegardenhelper.com/iris.html hope this helps and good luck with your
plants.your friend in gardening.mike57