How to Winterize Your Waterlilies

Cold weather can turn your beautiful water plants into mush. Here's how to save them.

Waterlily Pond

Waterlily Pond

Waterlilies bloom from tubers planted in ponds or tubs. They're tough plants, although tropical types need winter protection.

Photo by: Aquascape, Inc.

Aquascape, Inc.

Waterlilies bloom from tubers planted in ponds or tubs. They're tough plants, although tropical types need winter protection.

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If autumn leaves are littering your pond, get ready. Gardeners who live where winter temperatures drop below freezing need to prep their waterlilies for the cold. 

When it comes to these beautiful water plants, the tuber is the part that needs to survive, says Suzanne Boom, an operations manager for Lilypons Water Gardens, because that's where the plant's energy is stored. "Next spring,if the tuber survives, it will still start producing new roots and leaves."

It's not hard to winterize waterlilies. The most important thing is to know whether you’ve got a hardy or a tropical plant. If you're unsure, check the plant’s tag or label.

How to Winterize Hardy Waterlilies 

Wait until after the first frost to get your hardy waterlilies ready for winter, says Robb Lounsbury, a spokesman for the Aquascape Water Gardening Store and Inspiration Center. “Trim back the leaves killed by the first frost and cut the plant back to just above its crown. If potted, move the hardy waterlilies to the deepest part of the pond where they can remain throughout the winter season.”

Lilypons Water Gardens Water Lily George L Thomas

Lilypons Water Gardens Water Lily George L Thomas

'George L. Thomas' is a bright pink, hardy waterlily. It grows rapidly and spreads widely, so use it in a medium to large pond.

Photo by: Lilypons Water Gardens

Lilypons Water Gardens

'George L. Thomas' is a bright pink, hardy waterlily. It grows rapidly and spreads widely, so use it in a medium to large pond.

Hardy lilies will easily survive the winter outdoors in areas up to zone 4, Boom says. When they're left in a pond, the plants will go dormant.

If your hardy lilies are in an-above ground container, bring the container in, so it won't freeze and break. “Leave the plant in the pot, and put (the container) somewhere cool, like in your garage, until spring.” Don’t let the soil dry out. “Some varieties will produce tiny leaves right on top of the soil, and that will be the last step before they go dormant in fall. Cover the pot with wet newspapers to protect them.”

Don't have room for an entire container?  Just take out the tuber. “Put it in a jar with damp sand and keep it in the refrigerator," Boom says, and don't let it freeze. Keep the temperature around 40 degrees F. "The tuber will stay dormant until you’re ready to put it in fresh soil and move it back outside.”

Waterlily Nymphaea Chromatella

Waterlily Nymphaea Chromatella

Aquascape, Inc. recommends Nymphaea Chromatella, a hardy waterlily, for beginning water gardeners. It's easy to grow, with yellow flowers and dark green pads with bronze markings.

Photo by: Aquascape, Inc.

Aquascape, Inc.

Aquascape, Inc. recommends Nymphaea Chromatella, a hardy waterlily, for beginning water gardeners. It's easy to grow, with yellow flowers and dark green pads with bronze markings.

How to Winterize Tropical Waterlilies

Many gardeners treat their tropicals as annuals and toss the plants before a freeze. (Wait too long, and when the frozen lilies thaw out again, you’ll have to scoop dead, mushy plants out of your pond.) Boom says tropicals can survive outdoors over the winter only in areas like Texas and Florida in zones 8 and higher. If you live where the winters are cold, she recommends overwintering tropicals in the fridge, so you can control the temperature and force them into dormancy. 

Next spring, “Don’t bring them out too early,” Boom says. “They’re very sensitive to cold. Make sure the water temperature is up in the 70s.” A pond thermometer will give you an accurate reading; remember, air and water temperatures can vary. 

Lilypons Water Gardens Water Lily King of Siam

Lilypons Water Gardens Water Lily King of Siam

Waterlily 'King of Siam' is a tropical plant with purple blooms. Its lily pads have scattered brown freckles.

Photo by: Lilypons Water Gardens

Lilypons Water Gardens

Waterlily 'King of Siam' is a tropical plant with purple blooms. Its lily pads have scattered brown freckles.

Overwintering tropicals isn’t always a sure thing, she warns. “Tropicals are not meant to go dormant. They’re meant to grow all year long, so there’s always a risk that the tuber will die off.” That's why many gardeners enjoy them as annuals, growing them so they'll have a long period of blooms. The plants will flower until it’s just too cold for them, Boom says, which could be into October. “Hardies stop blooming and start going dormant in September.”  Tropicals are also popular,  even in cold winter areas,because they’re available in more colors. “There are no blue hardy lilies and only a few purples.”

Bloom says you can give tropicals a jump-start in spring by starting them indoors in an aquarium where the water temperature stays at least 70 degrees F. (You may need an aquarium heater to maintain this.) "The sooner the plants start growing in spring, the sooner they'll be big enough to start flowering. But day length also plays a role, so there is a limit."

Lilypons Water Gardens Lily Denvers Delight

Lilypons Water Gardens Lily Denvers Delight

This hardy waterlily, 'Denver's Delight,' opens flowers that range from white to pink to fuschia.

Photo by: Lilypons Water Gardens

Lilypons Water Gardens

This hardy waterlily, 'Denver's Delight,' opens flowers that range from white to pink to fuschia.

When your waterlilies are indoors, "place them in direct sunlight or purchase a quality grow light," Lounsbury adds. Despite your best efforts, tropicals are difficult to keep inside, he says, so don't be discouraged if you need to purchase new plants for the next growing season.

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