Aquatic plants not only beautify garden ponds, but they can help the pond biologically by helping to filter and aerate the pond water. Planting aquatic plants is different than planting garden plants. Aquatic plants are planted in floating baskets and lined with newspaper or untreated kitty litter. Floating aquatic plants have hair-like roots that protrude into the water and don't require soil. These plants absorb nutrients from the water - simultaneously keeping the water clean and oxygenating the pond. Popular aquatic plants for garden ponds include Marsh Marigolds, Water Hyacynth, Reed Maces, Water Buttons, Bog Primula, water violets and all types of water lilies. To prevent fish (especially Koi) from munching on your plants plant an inch of rock or pea gravel around the surface of each aquatic plant's basket. Aquatic plants baskets are priced between $2 and $4 online.