Overwintering Hardy Pond Plants

I have several aboveground water gardens, and overwintering the hardy marginal water plants in place in the ponds isn't what I want to do, so I put one of my small raised veggie garden beds to use for just this purpose. At the end of the season I pull the hardy marginal water plants from the small ponds and sink them, pot and all, into the ground for the winter. These veggie garden raised beds are the perfect place for that. They keep the potted pond plants all together in one location, and those beds won't be used till early spring, just about the time that I will clean up the ponds and get them started once again for the summer. Mine hold marginal plants, such as Water Celery, Corkscrew Rush, Miniature Cattails, Pickerel, Louisiana Iris, Ruby Eyed Arrowhead, Chameleon Plant, and American Water Willow.