Pickerel weed at my pond had a 50% come-back the first winter (maybe less), but those survivors have been reoccurring the last two springs. I think the trick is to get them established rather deep. My pond seems to get 10-12" of ice most years and I bet the PW established roots need to be a bit deeper than the ice gets. This year, the PW has been slow to show up and got hit by a couple of frosts. It's trying, but rather small so far....Fingers crossed for yours. The Thalia Dealbata (water canna???) is doing real well, however.
I am curious how your "yard iris" do at the pond. It's my assumption that the blue and yellow flag iris' are more adapted to being right at the water, whereas the common yard iris' may not like saturated soil...IDK.
I may hit you up for some buttonbush seed this year. I love that stuff and have none on my property.
