Whether waterlilies can remain in a pond during winter depends on whether they are hardy or tropical varieties. Hardy waterlilies can generally remain in the pond if protected from freezing, while tropical waterlilies must be brought indoors or stored in a frost-free environment in colder climates.
How do I overwinter hardy waterlilies?
Hardy waterlilies can remain in the pond throughout winter if their crowns are protected from freezing.
- Trim dead leaves and flower stems to approximately 2 in. (5 cm) above the crown.
- Move the waterlily, in its aquatic planter, to the deepest section of the pond where the water is less likely to freeze completely.
- Ensure the plant's crown remains submerged below the expected ice level.
Hardy waterlilies will become dormant during winter and resume growing when water temperatures increase in spring.
Can tropical waterlilies survive winter outdoors?
Tropical waterlilies cannot survive freezing temperatures. In colder climates, they should be removed from the pond before freezing conditions occur.
Options include:
- Indoor overwintering: Move the tropical waterlily into a heated indoor aquarium or container to maintain active growth.
- Tuber storage: Certain tropical waterlily varieties can be stored as dormant tubers in a suitable frost-free environment and replanted in spring. Storage requirements vary by variety.
- Replacement: Treat tropical waterlilies as seasonal plants and replace them the following growing season.
How do I overwinter a tropical waterlily indoors?
Tropical waterlilies can be kept actively growing indoors, although successful overwintering is not guaranteed.
- Maintain water temperatures above 70°F (21°C), preferably between 70–80°F (21–27°C).
- Provide strong, full-spectrum grow lighting for approximately 8–12 hours daily.
- Remove yellow, damaged, or decaying leaves as needed.
- Keep the plant in an aquatic planting container with its crown submerged.
- Avoid strong water movement directly over the plant.
Tropical waterlilies may produce fewer leaves and flowers indoors because of reduced light intensity and seasonal changes.
Do I need an aquarium heater?
An aquarium heater is recommended when indoor water temperatures may fall below 70°F (21°C).
- Use a thermostatically controlled aquarium heater to maintain consistent water temperatures.
- Select a heater appropriate for the container's water volume and depth.
- Follow the heater manufacturer's placement, operating, and safety instructions.
If the water naturally remains above 70°F (21°C), an additional heater may not be necessary.
Should I fertilize waterlilies during winter?
Winter fertilization depends on whether the waterlily is actively growing.
- Hardy waterlilies: Do not fertilize while the plant is dormant. Resume fertilization when active growth begins in spring.
- Tropical waterlilies: If the plant continues producing new leaves indoors, aquatic plant fertilizer may be used according to the product instructions.
- Slow or inactive growth: Avoid additional fertilizer when growth slows significantly, as excess nutrients may contribute to algae growth.
Note: Indoor overwintering does not guarantee tropical waterlily survival. Healthy plants may resume normal growth after being returned to suitable outdoor conditions in spring.