I have three siberian iris plants that have not been blooming. They bloomed the same year that I planted them but not since....it has been 4 years! They look very healthy and the foliage is beautiful. They are in a sunny location. Does anyone have any idea why they will not bloom for me??

I have the same problem. Siberian Irises like rich soil so I dug them all up and added lots of compost, I'll wait and see if they bloom next year. Did you check the roots? I also had an ants nest infiltrating the root section of my mounds.