Make floating islands. They control cattails and make a great cover for cool looking frogs. Do the islands prevent catkins from forming? One zillion seeds floating everywhere? Containerizing any rhizome plant is a temp fix at best. If the rhizomes don't break through the side, crawl out the bottom or over the top, it works well. I have a multitude of cattails, and lilies in containers right now. Let me know how that goes. Tell you one thing, those islands do look awesome.
