How to Grow Water Lilies in a Tub Filter

Plant water lilies in mid- to late spring, when the air and water temperatures warm. Even hardy water lilies do best with warm, gentle starts. Decide on locations for the water lilies where the plants have full sunshine, and move the pump and filter equipment to the other side of the pond. Water lilies float and are caught in pump and filter equipment if too close to the equipment.

Prepare wide, shallow containers for the water lilies. Ideal containers measure 6 to 10 inches deep and 12 to 18 inches wide. These containers provide balance through their heavy, stable bases. Fill each container 2/3 full of heavy topsoil or clay loam, and moisten the soil throughout. Don't use potting soil or compost, as these float in water.

Place the water lily rhizome at the side of the pot, with the growing end pointing toward the center and the top pointing toward the edge of the pot at a 45-degree angle. Cover the rhizome with soil, leaving the tip exposed. Lay ¾-inch layer of gravel over the soil to keep it in place. Push fertilizer spikes into the soil per manufacturer directions. These spikes provide long-lasting nutrition for the rhizomes.

Place the pots in your chosen locations at 6-inch depths. Run the filter and pump as usual for water movement and cleaning.

Move the pots deeper as the lily stems grow up to maximum depths of 12 to 18 inches. Never put the pots deep enough to submerge the foliage. Both pads and flowers need the air and sun to survive.