Winter Care for Pond Plants

• Water lilies are either tropical or hardy. Frank Lukasseck/Polka Dot/Getty Images

  Water gardens require special preparation in order for the plants to survive winter. Pond plants fall into two categories---either tropical or hardy. Tropical plants cannot survive cold temperatures, but even hardy plants require some special care to withstand winter freezing. Keeping the plants alive through winter means you don't have to purchase and pot new aquatic plants each year.

Winter Basics

• Winter preparation for the pond and plants begins in fall once temperatures drop below 60 degrees Fahrenheit. Stop fertilizing the pond plants, as any new growth put on late in the season is more prone to winter damage. Remove leaves and other debris that collects in the pond at this time of year. As the water begins to freeze, keep a small area of the water surface free from ice so that the water can remain oxygenated for any plants or fish that overwinter in the pond. If you have a shallow pond that freezes solid in winter, remove all plants or install a pond heater. Even hardy plants rarely tolerate total freezing.

Tropical Plants

• Bring tropical lilies and other tender pond plants indoors and set them in an aquarium or tub of water. Lilies and many other tropicals must be brought in once the outdoor temperature drops below freezing and the foliage begins to die off. More tender plants, such as cabomba, must be brought indoors before temperatures drop below freezing. Maintain a temperature between 50 and 70 degrees Fahrenheit in the room where the plants are stored during the winter. Most tropical plants do not go fully dormant, so they require some light throughout the winter months.

Hardy Plants

• Hardy plants overwinter in the pond, surviving freezing temperatures. These plants may go either partially or fully dormant during the cold. Many hardy plants have better survival rates when they are moved to deeper areas of the pond, as the water helps insulate against temperature fluctuations. Trim off the foliage from the plants once the first freeze causes the leaves to die back, then move the plants to a deeper area of the pond. The depth depends on the plant variety, but generally the top of the pots should set deep enough so that they are not in the ice layer that forms in the top few inches of the water surface.