Just stumbled over this thread,
Mary I over winter quite a few of my water plants in the Veggie Garden. Since I have several small ponds not deep enough to over winter all my plants. I dig up an area of my unplanted Veggie Garden each fall and put the pots in there and cover them over, then in the spring when it is time to start using the Veggie garden again I dig them up and put them in the ponds. Last year I did over winter a few of my water lilies that way and several of them did survive but generally I would put them in the bottom of my deepest pond and only put the more marginal plants in the ground to overwinter.
I wrote a very short article about Overwintering Hardy Pond Plants this way
http://garden.org/ideas/view/H...
I also use pieces of the mosquito Dunks in some of my still pots but only the ones that don't have fish or tadpoles those don't need them as the fish and tadpoles eat up the mosquito larvae before they are a problem. I don't really know what dragon fly larvae look like I will have to check that out. I do see dragonflies here from time to time.
