It's said that water iris Yellow Flag, and Blue Flag are the easiest to grow, and even invasive. I planted some, 4 yellow and 2 blue, last spring at the edge of a natural pond at the backyard. None come back at this point. What could be wrong? The site is east facing so they get sun until noon, then some evening sun.

Also a bit more in land I planted Goats Beard, Ligularia

Little Rocket, Rodgesia Chestnut, and Spiderwort, none came back either.

What came back are Japanese Variegated Iris, Siberian Iris, and Angelica (all about 1ft or so from water line), and to my suprise, Purple Rush (about 6" in water), which I thought has to be under 4ft of water to survive winter.

Your insight, and suggestions of other bogplants are greatly appreciated. Thanks!