Thanks, all.
I put each hardy in a 22" x 9" quarter barrel in early June so they are not pot bound.
Oh, and I really only have this problem with my hardies: Sunny Pink, Colorado, Texas Dawn & Attraction. The trops are better behaved.
My pond is between decks like a smaller version of minnowman's and all hardies and trops send pads out on the deck in a horticultural urban sprawl. I guess that's a pretty clear sign of waaay too many lilies. In addition to those hardies, I also have a lot of trops... in a 8x5 pond. I think the Sunny Pink alone would fill it.
It's a lifeboat situation. Arggghhh