Answer: As long as your pond is deep enough so that it doesn't freeze solid, hardy plants can be left in the pond, with marginals moved to the center where the water is deepest. Non hardy bog plants such as taro and papyrus may be brought indoors and kept in a sunny window with their pots set in a dish of water to keep the soil wet. Tropical water lilies are difficult to overwinter but you can try to do it by placing the roots in damp sand and storing them in a dark, cool (but nowhere near freezing)location indoors. Water hyacinths may also survive indoors if their roots are planted in a pot, the pot set in water and kept in the brightest location you have. I hope this covers the plants you might have.
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