I would say that planting in the pond bottom vs. pots depends on one's goals. I have seen beautiul waterlillies of many varieties grown in pots within larger ponds. The owner of the pond that I am refering to does not want the lillies to get out of control so he keeps them in pots and transplants as needed. I personally like a more self-sustaining system, so all my plants are planted in the pond bottom. If I had a pond denuded of vegetation, I would get the grass carp out of the pond.