Garden Fundamentals - Learn about plants and gardening

Water Lilies: Hardy and Tropical Water Lilies for Ponds

Water lilies (Nymphaea species) are extremely valuable to the pond. They not only look great and flower well, but the floating leaves provide shade, eliminating the light needed by algae. They also provide a hiding place for fish and other water creatures. Water lilies should cover half of the open water space to help maintain a balanced ecosystem. They do best in quiet water, so keep them away from fountains and waterfalls.

Water lily pond at Longwood Gardens, by Robert Pavlis

Water lily pond at Longwood Gardens, by Robert Pavlis

Water lilies can grow into large plants. The tubers elongate and divide each year, forming larger and larger clumps. Larger varieties will eventually take over the whole pond. They like lots of sun to bloom well, and if they are happy, they will bloom most of the summer and fall. In warm regions, they can bloom all year long.

Water lilies are available in two major categories, hardy and tropical. The hardy water lilies will grow well and overwinter outside in cold climates. The tropicals can also be grown in cold climates, but they need to be brought inside for the winter since they can’t take frost. The tropical plants are more trouble for gardeners in cold climates, but their flowers are larger and the colors are more luminescent. Many gardeners think the extra effort is worth it.

Water lily showing mottled leaf, by Robert Pavlis

Water lily showing mottled leaf, by Robert Pavlis

The plants themselves are available in various sizes. Small-leafed plants normally have smaller flowers and grow more slowly. Large-leafed ones have the largest flowers and grow faster. Medium-sized ones have characteristics half-way between the small and large. Match the size of plant to the size of pond. Large lilies should be given at least 100 square feet of open water space. The small ones will get lost in a big pond and are more suitable to small ponds and other small water features, including water tubs. These plants are quite adaptable to different water depths, but the large ones prefer being two to three feet deep and the small ones like to be 6 to 12 inches deep. If they are a bit too deep, it takes them longer to get leaves to the surface of the water in spring, but they will get there. Such plants will, over time, grow tubers higher up in the water to a level where they like to live.

Water lilies are heavy feeders, and many people feed them regularly, but that is not necessary. In a natural pond, the plants need to use the nutrients in the pond and not added fertilizer. In theory you could just lay the tubers on the bottom of the pond and they will grow. The problem is that the tubers float. Therefore it is better to put them into a pot along with some stones to hold them under water. Don’t use any soil or fertilizer. In a year or two, they will outgrow the pot, and you can just let them do their own thing at the bottom of the pond.

When you add a new water lily to the pond, place it on a shallow shelf for a while until leaves grow. Once it is established, lower it to its final depth. Water lilies naturally replace leaves every few weeks, those that are now too low will simply be replaced with leaves that have a longer petiole.

Hardy Water Lilies

Hardy water lilies grow in zones 4 to 11, and the flowers come in a variety of colors and shapes. Some even change their color as they age. Most varieties have green leaves, but some have a nice mottled color as well. For cold climate gardeners, these lilies bloom earlier in the year than tropicals, since they will bloom in colder water (60ºF). These easy-care plants have no problem with a winter freeze, provided that the tubers are below the ice. In warmer climates, they can flower all year long.

Water lily at Aspen Grove Gardens, by Robert Pavlis

Water lily at Aspen Grove Gardens, by Robert Pavlis

Hardies, as they are known, will open their flowers in the morning and stay open all day. Late in the day and on cloudy days, they will close. Each flower lasts three to five days, with new ones continually being formed. An established plant will have several flowers open at any given time.

The plants can be left alone to continue growing until they get too big. At some point, you will have to get into the pond and remove the whole clump. If you don’t do this every five years, the clump may get too big to remove. By this time, the plant will have made many side branches on the tuber, and you will be able to break or cut off any number of young growths. The rest can be given to friends.

Tropical Water Lilies

Tropical water lily, by Robert Pavlis

Tropical water lily, by Robert Pavlis

Tropical water lilies normally grow in zones 9 to 11, but they can be grown in colder zones as an annual. At the end of the season, bring them into the house over the winter and then return them in spring.

These lilies are available as day-blooming or night-blooming plants. Night bloomers, which tend to be more fragrant, will open their flowers at dusk and keep them open until about 10:00 am the following day, a couple of hours longer on cloudy days. Day bloomers open at about 9:00 am and close at 5:00 pm. People who work never see their day bloomers open except on weekends. Some varieties of day bloomers do stay open until late evening. All of these times are approximate and will change with climate, location, and variety.

Tropical water lily, by Robert Pavlis

Tropical water lily, by Robert Pavlis

 

The challenge with tropical water lilies in cold climates is overwintering them. They need to be kept at a minimum of 45ºF. The best way to do this is to remove the plant from the pond in fall and cut off all leaves and flowers. You will be left with round tubers the size of a golf ball or even smaller. Pack these in a glass jar along with some damp peat moss and store at 45 to 50ºF for the winter. In spring take out the tubers and warm them up so that they start to grow. Return them to the pond once the temperature stays above 70ºF.

Creating Natural Ponds

Learn how to create natural ponds without pumps, filters or chemicals:

 

Robert Pavlis
Editor of GardenFundamentals.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Fundamentals an educational site that helps you understand your garden better.

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