Even as the growing season slowly winds down, there are still many things the avid water gardener can do to keep his green thumbs wet. Besides seasonal pond maintenance, water gardeners in regions that experience freezing winters can focus their attention on autumn plant care. Savor the remaining water gardening season by providing the extra attention needed to properly winterize your plants.
Hardy Water Lilies and Lotus - If you have a deep water garden that will not freeze solid, hardy water lilies and lotus can be left in the water, as long as you sink them to deeper water for the duration of the winter. However, if you have a small or shallow water garden that freezes solid, they will need to be brought indoors for dormant storage, much like non-hardy marginal plants.
Non-hardy & Tropical Plants
Tropical Water Lilies - Plants of tropical origins, including many floating and submerged plants, will not survive the harsh winters of the northern tier of the United States. These plants are very sensitive to cold and need to be brought indoors. Saving just a few floating and submerged plants is sufficient since these fast-growing plants can repopulate themselves easily. Aquariums or large containers, such as a children's pool or RubbermaidTM container, are great for housing these plants. These tropical plants will need bright, supplemental lighting (a grow light or plant light) and heated water (at least 70°F) to over-winter successfully. Do not fertilize these plants during this period.
Proper autumn plant care ensures water gardeners are rewarded, for the time and effort they have invested over the summer, with the lush return of their pond plants in the following spring.