Many new water gardeners make the mistake of adding too few plants to their water garden. As a rule, try to cover about one half of the pond surface with plants. You can use plants like water lilies, water lettuce, and water hyacinths. Covering half the pond surface helps prevent excessive algal growth and provides shelter for the pond fish. Don’t forget to plant iris, taro, and other flowering and foliage plants.
The variety of aquatic plants available to the water gardener is almost limitless. Submerged potted plants such as Cabomba and Anacharis help to remove nutrients that promote algal growth. Use one bunch (usually six to ten plants) per 2 square feet of pond surface area. You can use fewer plants if space is limited. Be prepared to thin out and cut back the plants periodically to keep your water garden looking fresh.