How to Grow and Care for Water Lilies Indoors

Water lilies include several dozen plant species belonging to the genus Nymphaea. They are distributed throughout most of the world but native to South Africa, the northern hemisphere, and Australia. Although there are marked differences in the various species, water lilies are all prized for their great beauty. They typically grow with large floating leaves and delicate, often colorful flowers.

Water lilies are excellent plants in ponds or other large outdoor water features. Because they are such beautiful plants, many people wonder whether they can be grown indoors to enjoy daily. While it is possible to grow water lilies as houseplants, it's quite difficult. Ultimately, even if you provide the best growing conditions possible, you still may not get them to bloom. So if you do choose to try, be prepared for your efforts to fail at least as often as they succeed.

Can You Grow Water Lilies Indoors?

The basic requirements for successfully growing water lilies indoors are to provide carefully controlled water temperature and quality, and an exceptional amount of light. Few plants are more finicky about indoor conditions than water lilies, which is why indoor growing is usually pursued only by devoted enthusiasts. This is not an indoor plant suited for people seeking an easy-to-grow ornamental houseplant.

There are about 50 species of water lilies, as well as a considerable number of cultivars within those species. Although there are several ways to classify water lilies, including by their growth habit, they are most commonly divided into two groups: tropical and hardy water lilies.

Tropical water lilies are strictly warm-water plants with large and colorful flowers that are held on stalks above the water. There are both day- and night-blooming varieties. Flowers on tropical species are typically open for three to four days at a time, and the individual plants spread between three and 12 feet. These are some of the world's most prized water lilies, but they are not very practical for indoor growing due to their size and precise temperature needs.

Hardy water lilies grow in temperate regions, including throughout North America. They tend to have smaller foliage than tropical water lilies, and their flowers float touching the water. Hardy water lilies don't boast the same extravagant blossom colors as tropical water lilies. In many species, the flowers gradually change colors over the few days they are open. These are the best option for indoor growing since there are dwarf varieties that are well-suited for water containers of a manageable size.

How to Grow Water Lilies Indoors

Sunlight

To have any chance of blooming indoors, a water lily needs as much sun as you can provide—and probably more. These plants need at least four to eight hours of full, direct sunlight a day to thrive.

Artificial Light

Unless you're lucky enough to have a sunroom or heated greenhouse, the lack of direct sunlight in homes during the winter makes it almost certain you will need to add supplemental light to get water lilies to thrive and bloom. Place the grow lights directly above the plants and run them for 12 to 18 hours a day to provide the equivalent of eight hours of sunlight. It may take some experimentation with different types of light bulbs and fixtures to get the lighting right.

Temperature and Humidity

Make sure the water is at the proper temperature for the water lily species you are growing. Tropical water lilies will die at water temperatures below 60 degrees Fahrenheit, and most need water temperatures above 70 degrees Fahrenheit to thrive and flower.

There is no strict water temperature requirement for hardy water lilies. The 68 degrees Fahrenheit that is common for indoor winter temperatures will work fine for hardy water lilies, but you should keep the temperatures steady rather than allowing for lower nighttime setbacks.

Where necessary, consider adding an aquarium water heater to keep the temperatures at the ideal level for the water lilies you are growing.

Watering

When the tank or container gets low on water, add spring water or distilled water that has been allowed to reach room temperature to bring the water level back up. Ideally, the top of the growing basket should be submerged by at least 12 inches. If you must use tap water, let it sit for at least 24 hours before adding it so the dissolved chlorine can evaporate out.

Water Circulation

An air bubbler, of the same time used in fish aquariums, is a good idea for indoor water gardens, as it will keep the water aerated and prevent it from becoming stale and smelly. Properly aerated, you will not need to change the water as often.

Fertilizer

Water lilies will do best if you add liquid fertilizer or fertilizer pellets for aquatic plants to the water. When you add additional water to the tank, a small amount of additional fertilizer should be added.

Pruning and Maintenance

Remove dead leaves as they appear; this will keep the water fresh and prevent it from stagnating. One of the major drawbacks to growing water lilies indoors is the smell of stagnant water, though murky water shouldn't damage the plants. It's okay to change the water every so often.

Container and Size

Water lilies, like other water garden plants, are grown in porous net baskets submerged in a larger water container or pond. If you want to grow tropical water lilies indoors, the water container will need to be quite large. Although estimates vary depending on the species, it's a safe bet that each tropical water lily needs about 36 square feet of water surface area to thrive. In practical terms, this means a 6 x 6-foot body of water. This is not an option inside most residences unless it is equipped with a greenhouse or large sunroom devoted to the purpose.

Therefore, the only practical option for most people is to grow hardy water lilies. Some dwarf varieties of hardy water lily can grow successfully in containers as small as 15 gallons, such as a moderate-sized fish tank or galvanized washtub. The plants themselves are placed in a net pot or planting basket filled with a growing medium. For indoor growing, the basket needs to be small enough so that water can flow freely all around the basket, and short enough so that the top of the basket can remain submerged well below the surface of the water tank. For many species, the water level should remain 12 inches or more above the top of the net pot holding the plant.

Potting Soil and Drainage

While water lilies are fully aquatic, they will still need a growing medium. The best option is to fill a plastic net pot or planting basket with rocks at the bottom to weigh it down and then add a growing medium, such as sand, perlite, or aquatic planting mix.

Potting and Repotting Water Lilies

After filling the net pot or planting basket with a growing medium, bury the plant in the pot so that the growing tip is just slightly exposed but the entire rhizome is buried. Lower the pot into the water container so water can freely circulate around it. Once potted, your water lily should not require repotting; it's best to start over with a new plant once the water lily becomes mature and overwhelms its tank.

Moving Indoor Water Lilies Outdoors

It's usually not very practical to move water lilies being grown as indoor houseplants to outdoor locations, A water lily accustomed to an indoor water tank does not react well to the shock of being removed and dropped into an outdoor pond where the water temperatures and chemistry is much different. One possible exception is if the entire indoor water tank can be wheeled to an outdoor patio location for the warm summer months. Even here, the shock is often more than the plants can bear. If you are growing water lilies as indoor houseplants, it's best not to tempt fate by moving them back and forth.

Overwintering Outdoor Water Lilies

In cooler climates, it is quite common to overwinter outdoor aquatic plants by bringing them indoors. But the goal here is not to use them as indoor flowering plants, but simply to preserve them in a dormant state over the cold months so you can move them back outdoors the following summer.

With tropical water lilies, overwintering means bringing them indoors and placing them in a water tank with carefully controlled temperatures. However, growers generally encourage them to go dormant by cutting back much of the foliage during this time. There's no effort to keep outdoor water lilies blooming during the overwintering period when they are brought indoors.

With hardy water lilies, overwintering is often done by removing the potted plant from the outdoor pond, cutting back the foliage, sealing it in a plastic container or bag, and placing it in a cool basement or heated garage at about 50 degrees Fahrenheit for the entire winter. When moved back to the outdoor pond in late spring, the plant typically leaps out of dormancy and begins actively growing again.