Hardy water lilies (Nymphaea spp.) have circular leaves with smooth, rounded edges and waxy surfaces. They bloom in a variety of colors, including shades of white, yellow, pink, red and orange. Hardy water lilies begin blooming early in the springtime, as soon as water temperatures reach a steady 60 degrees F. Unlike tropical water lilies, hardy water lilies can over-winter in ponds throughout a wide range of climatic regions. Hardy water lilies are have shallow roots systems composed of rhizomes, and their lily pads spread rapidly over the pond's surface.
Submerge your hardy water lily to a depth of about 12 to 18 inches, so that the leaves and flowers are resting on the water surface. Place the hardy water lily in a spot in your pond that has full sunlight all day.
Feed your hardy water lily once every four to six weeks throughout the spring, summer and early autumn with all-purpose aquatic plant fertilizer tablets. Follow the fertilizer instructions on the label and stop fertilizing the hardy water lily in September.
Trim off yellowing leaves and old flower blossoms throughout the spring, summer and early autumn.
Prune away the dead leaves and stems of the hardy water lily after the first killing frost in late fall or early winter, removing about two-thirds of the plant. Submerge the hardy water lily into the deepest part of your pond for the winter.
Divide your hardy water lily plants once every two to three years in spring. Remove the water lilies from the pots, rinse the soil from the rhizomes and cut a 3-inch-long segment of the rhizomes. Repot the divided lilies into fabric pots with fresh garden topsoil.