Tropical water lilies offer the water gardener colors and fragrances not attainable with hardy lilies – large size and quantities of blooms, a full range of color, night bloomers, and stronger fragrances. These very desirable plants have everything to offer the gardener, except a guaranteed return appearance in the spring. Because they are tropical in origin, like hibiscus and bougainvillea, they do not have a short day-induced winter dormancy period which would enable them to survive cold weather. For this reason, tropical water lilies must be considered annuals in the outdoor pond unless they are given special treatment to be overwintered.
The most simple and successful way to ensure your lily’s survival through the winter has been the same answer for tropical flower gardeners for decades: bring the lilies into a greenhouse in a tub or tank. Keep the lily small by withholding fertilizer. When the weather warms and summer comes, they can be repotted and placed back into their pond home for another summer season.
Gardeners without a greenhouse can take advantage or a technique developed for propagation purposes to bring their lilies to spring. Preparation for winter storage begins before summer is over. Fertilize the lily in early September for the last time. The plant will become starved and overcrowded and start to make a tuber, its natural response to bad conditions. Leave it in the pond until all the leaves are dead. This may take until after the first few light touches of frost. Feel the plant’s root – a hard tuber must be formed for it to be stored successfully. Remove the lily from the pot and rinse it off thoroughly. The tuber may be as large as a fist or as small as an acorn and there may be multiple small ones around a large one. Save the small tubers since they are more likely to make good plants next spring than a larger one. If the tuber still has root or stem tissue attached, let it air dry for a few days. The tissue will then snap off cleanly since a callus will have formed to protect the tuber from dehydration. Wash the tuber well and place it in a plastic bag or jar filled with distilled water. Store it in a cool, dark place. Check the container monthly and if the water is foul or discolored, change it for fresh water.
To start spring growth, place the container in a bright, warm place. When sprouts emerge, pot the tuber in a shallow pan of sand. Place it in a larger container of water so that developing leaves can float. Keep the container in a sunny, warm spot (water temperatures should be about 70-75 degrees). You may need to use a small aquarium heater and/or supplement natural light with a fluorescent grow light. When the leaves grow up to the water’s surface and white feeder roots can be seen, snap the little plantlet off the tuber and pot into a standard growing container. Place in the outdoor pond when water temps are at least 70 degrees consistently. Discard the old tuber. The new plant, given warm water, fertilizer, and lots of sunlight, will make a full-size, blooming plant very soon. Don’t rush it if the water temps aren’t up to 70 degrees or more consistently. The lily may slip back into dormancy.
Please ask us any questions you may have about overwintering your tropical lilies. We’re happy to help!