heres one example of water lilies planted directly in the pond , about 10 12 years ago , my friends pond. the liles own the pond, they are every where from 1 ft to 6 ft deep , you can only fish top water weedless or plastic weedless. there's bout 2 ft of muck in the pond from them not being trimed in the fall or removing dead stuff during the summer, only way he is going to make it nice is a long reach track hoe and clean it out. in containers i can control them 100%. i don't want my hard work ruined . the maginals i'll plant in 6" commercial gutters and i can move in and out as the water level drops,if need be. just some ideas. bank plants you always cut back.
