Released May 4, 2009
URBANA, Ill. -- Waterlilies and lotus are very popular water garden plants, noted a University of Illinois Extension horticulture unit educator.
"They offer an exotic-looking touch to any pond," said Jeff Rugg. "Some dwarf varieties of each are capable of being grown in tubs on the patio or deck. All are easy to grow in containers or in backyard ponds."
An individual flower from these plants will only last a few days, but a healthy plant can have several flowers blooming every day from June to August or even later.
'Hardy waterlilies only bloom during the day," he said. "Tropical waterlilies come in varieties that bloom in the daytime or others that bloom at night. Night bloomers are also usually very nicely fragrant.
"Dwarf lotuses that can grow in a bowl or small, water-holding container have flowers as small as a tennis ball, while giant lotus have flowers as big as a basketball. They can be planted in pots or even right into the gravel of a backyard pond when they are dormant or when they are actively growing."
This is a nice feature, he added, because they are often ordered through mail-order catalogs and can arrive as a dormant rhizome or after being harvested from a pond with leaves and roots hanging all over.
Waterlilies come in hardy and tropical species and varieties. Hardy ones can tolerate cold water and are often left in the bottoms of northern ponds over the winter.
"As long as the ice doesn't form around the roots, it will come back fine," he said.
"Tropical waterlilies need to stay in warm water. In northern ponds they are often treated as annuals. Some gardeners will overwinter the tropical tuber in damp sand or moist soil and occasionally are successful in growing them more than one year."
Hardy waterlilies sprout roots and leaves from the rhizome that grows horizontally an inch or two deep in the mud. When you plant one in a pot, just set it on the clay soil and cover it with an inch of soil and an inch of pea gravel to keep the fish from spreading the mud into the pond.
"Waterlilies grow best in the awful clay soil that many of us have in our gardens," said Rugg. "This is the normal mud that holds water in a pond so it is great for water plants. Don't use a nice bagged mix full of peat moss or topsoil for waterlilies and lotus as it will float out of the pot and cause a huge mess in the pond.
"If there are large fish that can knock the pea gravel off the top of the clay, just use bigger gravel, but don't bury the growing point of the tuber under a rock. If you don't have any clay soil available, use kitty litter since it is just clay soil. Don't use any special litter mix that has deodorizers or other ingredients, just use the generic stuff."
The leaves on a waterlily gather oxygen and send it down to the roots and rhizome, potentially causing the plant to float out of the pot. Until it is well rooted into the new soil, it may be necessary to place a large rock on top of the rhizome to hold it in place.
Some hardy waterlily rhizomes will grow more than foot long in a summer. It might grow right over the edge of the pot.
"Dividing a rhizome is easy," he said. "They should be divided in early spring just before the new growth starts, but they can be divided during the summer when it is easier to see where the growing points are. Each growing point will have a set of leaves, kind of like eyes on a potato.
"Cut the rhizome into sections several inches long, each with a growing point, and toss any old sections that don't have any eyes."
If an actively growing waterlily or lotus is purchased in a pot from a location that has warm water, don't stick it in a pond with cold water. Many sales locations grow lilies and lotus in greenhouses. They get an early start and look wonderful at the greenhouse.
"If your pond water hasn't warmed up yet and you put the waterlily or lotus in water 10 or more degrees colder, the plant may go dormant or at least stop growing for a month or more," Rugg cautioned.
"Never put tropical waterlilies in water cooler than 70 degrees. Dormant lotus tubers can be planted in water as cold as 65 degrees, but once the plant is starting to grow, water in the mid 70s to mid 80s is preferred."
Waterlilies and lotus are all heavy feeders. Slow-release fertilizer tablets are best. Insert them into the pot according to the label directions. Some will dissolve in a week or two, and others are designed to last for months. Always press them into the soil as deep as they can go, then press the soil in over the hole to keep the fertilizer in the pot and not dissolving out into the pond water.
"If you are growing the lilies or lotus in their own container on a patio, you can add liquid fertilizers to promote more flowers," he said. "This may increase the amount of algae. If the water in the container turns green, drain it out and refill with clean water.
"Keep waterlilies and lotus well fed, in warm water, in full sun and you will be rewarded with beautiful flowers."
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http://www.aces.uiuc.edu/news/stories/news4774.html
Contacts: Jeff Rugg, (630) 553-5823
Bob Sampson, (217) 244-0225, rsampson@uiuc.edu
