Nymphaea (Water Lily)

Hardy versus Tropical Water Lily

There are two main types of water lilies: hardy and tropical. Hardy water lilies (hardiness zones 3-11) will survive winter dormancy if their rhizome does not freeze (planted below the freezing line). Tropical water lilies (hardiness zones 9-11) must be stored over the winter or treated as annuals.

Aside from cold hardiness, the main differences between hardy and tropical water lilies are the following:

• Hardy lilies open in the early morning and close in the late afternoon. Tropical lilies come in day-blooming varieties and night-blooming varieties.
• Hardy lilies are available in red to almost black, pink, white, yellow, orange, or peach shades. Tropicals come in a wider range of colors, including blues and purples.
• Some hardy water lily flowers change color shades over the flower’s 3 to 4-day bloom period.
• Tropical lilies have longer stems that hold their blossom higher above the water’s surface.
• Tropical lily pads are usually thin with slightly scalloped or toothy edges. They can be solid green, flecked, mottled, or whorled with maroon or bronze. Hardy lily pads are usually thick and leathery with smooth edges. They can be solid green or lightly mottled with maroon when young.
• Hardy lilies are grown from rhizomes, which bear small bumps or eyes that will sprout into a new plant. Tropical lilies are grown from bulbs, producing baby bulbs that can be repotted into their own pots.
• Tropical lilies tend to be more fragrant.
• If fertilized properly, tropical lilies will bloom at least 20 times more often with larger blooms than hardy lilies.

How to Care for Water Lily

• Water lilies prefer six or more hours of sunlight. Some tolerate part shade.
• They thrive in loamy soil in neutral to slightly alkaline, undisturbed water.
• Plant your tropical lilies in the center of the container, with the crown resting just above the soil’s surface. Tropical lilies should not be set out in the water garden until the water temperature has stabilized at 70ºF (20ºC).
• Plant your hardy lilies at the edge of the container at a 45-degree angle so that the growing tip rests slightly above the soil level. Cover the soil with gravel or a thin layer of sand. The container should be large enough to allow the rhizome to spread.
• Water lilies can be quite specific about the depth of water they need. Planting too high will cause hardy plants to freeze in winter; too low will prevent young plants from receiving adequate sunlight. Miniature and dwarf lilies can be planted 6 in. deep (15 cm), medium to large lilies can be planted 18-30 in. deep (45-75 cm), and very large lilies can be planted up to 48 in. deep (120 cm).
• With new plantings, initially place the pot just below the surface of the water and gradually lower it as the water lily grows. Once the plant is established, the pot can remain at the desired depth.

• Ensure your water lilies do not cover more than 65% of the surface area.
• Feed during the growing season with a proprietary aquatic fertilizer. Fertilize hardy lilies once a month. Tropical lilies are heavy feeders and should be fertilized every 2-3 weeks during the growing season.
• Cut the dying flowers as they sink below the surface to promote many blooms. Follow the stem down as far as it goes and cut or snap it with your fingers.
• Remove yellow leaves regularly.
• Keep an eye out for water-lily beetle, water lily aphid, brown china-mark moth, false leaf-mining midge, crown rot, brown spot, and leaf spot.
• Propagate hardy lilies by division for exact duplication from seed for variation. Propagate tropical lilies from tuber and division for exact duplication from seed for variation.
• Tropical lilies can be stored over winter by lifting the plant from the container and storing the rhizome in a plastic bag or container full of damp sand and peat moss at 50-55ºF (10-12ºC). Trim the roots and cut back most of the leaves. Store it in an aquarium tank making sure that the temperature remains below 68ºF (20ºC).