Place three slow-release fertilizer tabs at the bottom of a plant container that is 12 inches wide and 4 to 5 inches deep. Cover the tablets with loamy garden soil. Fill the pot with good garden soil until it is within 1 1/2 inches of the top edge.
Insert the lily rhizome into the soil horizontally, so the crown of the rhizome protrudes above the soil surface. Cover the soil with 1/2 inch of additional soil, then fill the pot the rest of the way with pebbles. Water the soil until it is soaked.
Place the container in at least 12 inches of water in your pond, but no more than 36 inches of water. Remove the containers every year in the spring and divide the plants, replanting them in the same way that you planted the original.