Here in MN I've had both yellow and purple irises planted along my bank for about 5 years. They have just barely spread beyond the original area they were planted. Some plants might cover an area the size of a circle 1 foot diameter. I have a plant in the bog next to the pond that has been there 10 years and it's about 2 feet diameter. They don't seem to present the same problem here.


Gotta get back to fishin!