Some of the most spectacular additions to backyard ponds, fountains, and other ornamental water features, water lilies are the queens of all flowering floaters. The rich history of this culturally important genus is only rivaled by the modern-day diversity of its cultivars. Beloved by horticulturists and pond enthusiasts alike, Nymphaea has now been determined to have a cosmopolitan distribution. Its alluring features naturally grace the pristine wetland systems of tropical to temperate regions.
Also known as water nymphs, these members of the Nymphaeaceae family are known for their rounded, floating leaf pads. Those of the largest species measure more than an entire foot (30 cm) across, while those of miniature cultivars are about the size of a small coin. Serrated or smoothly-margined, the leaf pads are attached to lengthy petioles which extend from rooted rhizomes.
Depending on the species, solitary blooms begin to appear in spring or summer. These either float on the surface or fully emerge to suspend their dozens of petals in the air. The petals range in color from white to yellow and peach to deep pink, with hues that may intensify over the course of a few days. Due to their fragrant and immaculately white flowers, the most popular species include the pond lily (N. odorata) and the European white water lily (N. alba).
Facts, Benefits & Uses of Water Lilies
Water lilies are the perfect aquatic plants for adding color and texture to a pond’s surface. Their presence naturalizes and helps soften the appearance of even the most modern and rigid pond designs. Apart from their visual appeal, they bring a wealth of ecological benefits to just about any water feature, natural or artificial, that they are grown in.
As their water-resistant, floating leaves create shade, water lilies help regulate water temperatures and prevent algal buildup in outdoor ponds. The leaves and submerged structures aid in removing excess nutrients from the substrate and water column, improving water conditions for fish and amphibians. These freshwater creatures also benefit from the structure provided by the petioles and leaves. They can use them to hide from potential predators.
Water lily blooms help diversify pond gardens because they attract many pollinators, including beetles. Tropical water lilies, which may bloom at night and during the warmest summer days, can draw nocturnal insects to the pond. Hardy water lilies, on the other hand, bloom early in spring and attract daytime pollinators.
Water Lilies Growth, Hardiness & Climate
Water lilies are versatile plants that can be grown in practically any type of outdoor water feature. Smaller cultivars can be placed in large bowls of water. Larger cultivars require moderately deep and wide ponds, where their leaves can expand without structural limits. As they have both floating and submerged structures, they require an adequate depth to accommodate the full length of their petioles.
Categorized into two main groups, Nymphaea spp. may be “tropical” or “hardy” water lilies. Those of the tropical kind are more suited to warm conditions and tend to be characterized by larger and showier features. These are highly sensitive to cool temperatures and may fail to survive through a harsh winter. In contrast, hardy water lilies may tolerate sub-zero temperatures if they are overwintered correctly.
Both types of water lilies develop their colonies via rhizomatous growth. For this reason, many pond owners may wish to restrict their spread to aquatic baskets or submerged pots. These can be moved deeper into the pond as their petioles lengthen. Keep in mind that their best growth rates usually occur in areas with calm water and full sun exposure.
How to Plant Water Lilies
Water lilies are best planted in late spring to summer, when ambient conditions encourage rapid germination. Depending on the species, these aquatic plants can be grown using bud cuttings, root divisions, plantlets, or seeds. If you intend to grow your lilies from seed, these should be sown once they are ripe. The most viable ones are those which have yet to dry out. Sow these in a free-draining germination mixture (or use the water propagation method) and keep the seeds submerged under about 1 – 2 inches (2.5 – 5 cm) of water.
As the seeds germinate and produce their first leaves, gradually move them into larger and deeper containers of water. Plantlets should similarly be allowed to root in aquatic compost and gradually placed in deeper conditions until their petioles are long enough to reach the surface along the pond’s margins. Pots can be moved deeper into the pond once the leaves and new petioles show signs of rapid growth.
Cuttings and tubers may be planted directly into the pond’s substrate or in pots (at least 6 – 8 inches or 15 – 20 cm deep) and aquatic baskets that are ready to be submerged. To weigh them down, place a layer of aquatic gravel on the surface of the substrate. The tip of the tuber should barely peak through the surface of the soil. In optimal conditions, new leaves should gradually make their way to the surface.
How to Care for Water Lilies
Keep your lilies in the sunniest parts of your pond. When they are afforded full sun exposure and a balanced mixture of nutrients, they tend to have rapid growth and flowering rates. Though some tropical water lilies can thrive and annually produce a sufficient number of blooms under partial shade, many require at least 6 – 8 hours of direct sun to bloom.
Pumps or filters should be placed away from Nymphaea spp. as they prefer still water. To keep the rhizomes at an ideal depth and temperature all year round, ensure that they are placed at least 4 – 18 inches below the surface. Mature specimens of larger species can be placed even deeper. Pond water should have a sufficient amount of nutrients, especially if fish waste is present. If there is a shortage, nutrients can be supplemented with the addition of fertilizer tablets. These will need to be pushed into the substrate each spring.
To maintain the appearance and overall health of your lilies, aim to deadhead flowers as soon as they have begun to die back or fade. Deadheading should prevent them from attracting potential pests and decaying on the water’s surface. To minimize plant waste, cut the floral stalks down to the crown. Leaves with signs of damage or fungal problems should also be removed.
To prevent your lilies from growing in a congested manner, divide their rhizomes every few years. Root division should help refresh older plants, allowing them to reallocate nutrient stores and produce more young roots and leaves.
How to Winter Water Lilies
Hardy water lilies can easily tolerate mild winter conditions and can be left outdoors through the season. As their leaves will naturally begin to die back as soon as temperatures drop, you may cut them down to the crown. Remove any decaying plant material on the pond’s surface. Move the potted rhizomes deeper into the pond (if possible) to prevent the crown from becoming too chilled.
Tropical water lilies are much more sensitive to the cold and may not survive through frosty winters. If you live outside of USDA hardiness zones 9 – 11, you will have to consider transferring your lilies to an indoor location. You may also cut them back, collect and store their rhizomes, and replant them the following year. Rhizomes should be kept in damp sand and moved to a location where temperatures do not dip below 10˚C (50˚F).
Are Water Lilies Invasive or Toxic?
As water lilies spread via a network of underground rhizomes, they can rapidly colonize calm waters and choke them of light and oxygen. If you intend to grow a non-native species in your area, make sure its spread is limited to within containers in your pond. Note that wild visitors or overflowing ponds can lead to the dispersal of viable seeds and self-propagating fragments.
Water lilies are considered poisonous plants because they contain nupharin, an alkaloid that can cause toxicity symptoms when consumed in large doses. Nupharin concentrations vary across species and between major plant organs, though the seeds are usually free of this compound.
Despite its neurotoxicity, nupharin can easily be neutralized to render lilies safe for consumption. Nymphaea are thus considered a type of famine food. Although some water lily species are considerably less toxic than others, it is advisable to keep a close eye on pets and children that may interact with them.
Are Water Lilies Edible? Do Animals Eat It?
Apart from the European Nymphaea species, which have the highest amounts of nupharin, water lilies are generally safe for human consumption. For safety and culinary purposes, they are usually boiled before they are consumed. The tuber is considered the most edible and useful part as it can be ground into flour or boiled and roasted whole. Young flowers and leaves are safe enough to consume raw.
Many wild animals in wetland regions may occasionally consume the tubers, leaves, and seeds of water lilies. The American white water lily (N. odorata), for example, is eaten by small mammals and waterfowl. Herbivorous freshwater fish, such as grass carp, may also eat young lily leaves and their submerged structures.
Where to Buy Water Lilies & Seeds? (UK & US)
Nymphaea can be purchased in many plant nurseries and aquascaping stores all across the globe. As dozens of cultivars are now propagated to meet international demand, it’s possible to purchase a selection that produces a wide range of bloom colors within a single season. When deciding on the perfect types of water lilies for your pond, make sure to consider their depth and surface area requirements.