Whether you’re planning to grow water lilies in a pond or a container water garden, the planting process remains unchanged. Begin by planting the water lily into a small container that can be placed inside a tub or a pond.
Select a container with a diameter of 12-20 inches and a depth of 8-10 inches. Cover the drainage hole with mesh or burlap to prevent soil from escaping. As the plant grows based on the size of the container, choose a smaller pot if you’re working with a small tub instead of a pond.
Fill two-thirds of the container with aquatic gardening soil or typical garden soil as opposed to lightweight potting mixes containing vermiculite, perlite, or peat. It should be heavy. Position the rhizome along the edge of the pot, with the growing tip pointing upwards. At an angle of around 45 degrees, direct it toward the center of the container. Cover everything except the tip with soil and add a layer of small rocks or pea gravel to keep the soil in place.
Place the planted pot into the pond or tub at an angle to let air escape. Set the base of the container 12-16 inches deep. As the plant develops, its leaves will float to the surface. If your plant has already begun producing leaves, position the container in such a way that the leaves are submerged 6-8 inches deep initially. After some days, the leaves will reach the surface, and you can lower the plant to its final depth of 12-16 inches.