The water lily has a floating leaf and its flower blooms above water. It is among the most widespread of all plants grown in water gardens. Water lilies also grow in ponds and slow-moving bodies of water.
Although the leaves of water lilies (Nymphaea spp.) float on water, the stems and roots do not. Water lilies need soil to grow as opposed to free-floating aquatic plants such as water lettuce, hyacinth or duckweed. They can grow on the bottom of a pond or stream or in a pot full of soil submerged under the surface of the water.
Water lilies come in two types: tropical water lilies, which bloom either at night or during the day and hardy water lilies that bloom during the day, according to Aggie Horticulture. While hardy water lilies prefer to grow submerged in water 12 to 18 inches above the top of the pot, tropical varieties prefer water depths of 12 inches, according to the University of Illinois.
Water lilies usually need protection over the winter months, according to the University of Illinois. Protecting hardy water lilies over winter months usually involves removing them from the water and allowing them to go dormant, while protecting the roots from freezing or drying out. Protecting tropical water lilies involves repotting them and storing them in an aquarium with plenty of light at 20 degrees Celsius.