Nymphaeaceae is a family of flowering plants, commonly called water lilies. They live as rhizomatous aquatic herbs in temperate and tropical climates around the world. The family contains five genera with about 70 known species. They thrive in ponds, lakes, and slow-moving bodies of water, where they provide ecological and aesthetic benefits.
Most species of water lilies have rounded and variously notched waxy-coated leaves on long stalks that contain many air spaces and float in quiet freshwater habitats. The stalks arise from thick fleshy creeping underwater stems that are buried in the mud. The showy fragrant solitary flowers are borne at or above the water surface on long stalks that are attached to the underground stems. Each cuplike flower has a spiral arrangement of its numerous petals.
Water lilies provide food for fish and wildlife but sometimes cause drainage problems because of their rapid growth. Many varieties have been developed for ornamental use in garden pools and conservatories. Many water lilies are easy to grow and reward the gardener with fragrant and sumptuous blossoms from June until October. The plants are best planted in spring. Water lilies start faster and have a faster growth rate.
Characteristics
- Leaves: The leaves of water lilies are round, flat, and often have a characteristic slit from the edge to the center, which allows the leaf to fold down for easier emergence through water. They are typically green on top with a purplish hue underneath, floating on the water’s surface or slightly above it.
- Flowers: Water lily flowers come in a spectrum of colors including white, pink, yellow, red, blue, and purple. They can be day-bloomers or night-bloomers. The flowers rise above the water’s surface on long stalks and can be quite large, with some species having blooms up to 12 inches across.
- Growth Habit: Water lilies can be tropical or hardy (temperate). Tropical varieties might not survive cold winters, whereas hardy varieties can regrow from rhizomes each spring. They grow from rhizomes, which are horizontal stems that root in the pond’s mud.
- Roots and Rhizomes: Anchored in the muddy substrate at the bottom of the water body. Rhizomes are thick and store nutrients for the plant.
- Ecological Role: They provide shade, reducing water temperature and sunlight penetration, which helps in controlling algae. Their presence also offers habitats for fish and other aquatic life.
Cultivation of Water Lilies
- Planting: Water lilies are typically planted in containers or directly into the pond bed, but containers are preferred for control over growth. The rhizome should be planted horizontally with the growing tip pointing upward, covered with a few inches of soil or aquatic planting medium, and then topped with a layer of sand or gravel to prevent the soil from floating away. The container or planting site should be placed in water at least 12 inches deep.
- Water Depth: Different varieties require different water depths. Hardy water lilies usually grow in water 18-30 inches deep, while some tropical varieties might need deeper water. The depth of planting should be adjusted based on the plant’s size and vigor.
- Light: Water lilies thrive in full sun. They need at least 6 hours of direct sunlight to bloom profusely. Less light will result in fewer flowers.
- Fertilization: They benefit from fertilization during the growing season. Specialized aquatic plant fertilizers can be placed in the soil or directly into the growing container. Over-fertilization can lead to algae problems, so it’s important to follow recommended guidelines.
- Maintenance: Pruning old or dead leaves and flowers not only keeps the pond looking tidy but also encourages new growth. Removing spent blooms before they seed can prevent unwanted spread. Monitor for pests like aphids and beetles; rinse leaves or use insecticidal soap if necessary.
- Winter Care: For hardy water lilies, simply lower the container to the deepest part of the pond where the water won’t freeze solid, or cover the pond with a net to catch falling leaves. For tropical varieties in colder climates, they might need to be overwintered indoors in a warm, dark place, or treated as annuals.