How to Care for a Waterlily Indoors Growing in Dirt

Choose an area of your indoor location that features about six hours of sunlight daily. Select a planting pot for your waterlily that is about 10 inches deep and 15 inches wide. Purchase an aquarium that is about 30 inches tall as well, and test the water temperature to ensure it is at least 68 degrees Fahrenheit.

Fill the planting pot with clay loam potting soil so that it is about two-thirds full. Look for the growing point on the water lily starter plant, which is a bud that looks like the eye of a potato. Situate the waterlily rhizome -- the horizontal underground plant stem -- in a way that allows the growing point to be directed toward the center of the planting pot and at a slight angle so that the plant grows across the center of the container. Make sure the rhizome rests slightly above the soil’s surface, and cover the rhizome lightly with soil.

Put pea gravel on top of the soil, allowing the gravel to form a 1/2-inch to 3/4-inch layer, which keeps the soil from floating in the water in which you must place the waterlily plant as well as keeps aquarium fish from burrowing in the soil. Keep the pea gravel away from the rhizome.

Water your waterlily plant so that the soil is moist. Gently place the waterlily planting pot into your aquarium, allowing at least 8 inches of water to be above the pot’s top if the plant receives at least six hours of sunlight a day. If the plant fails to receive this much sunshine, make sure about 6 inches of water is above the waterlily so that the plant still has access to adequate sunlight. Place the planting pot on top of items such as bricks to get the pot at the right distance from the top of the aquarium.

Continue to lower the bottom part of the waterlily planting pot as the plant grows taller. Strive to get the plant to a position in which you have 1 to 1.5 feet of water above the top of the plant, as this is the plant’s optimum growing depth.

Put a slow-release fertilizer tablet in your waterlily aquarium, following the manufacturer’s instructions. Select a 20-10-5 fertilizer to help the plant flourish.