Autumn Aquatic Plant Care: How to Prepare Your Water Plants for Winter
With the shorter days and cooler weather comes a change in foliage. For trees, we get to enjoy the vibrant fall colors that remind us of apple picking, pumpkin patches, and playing in the leaves. However, the same does not happen for our water plants. Colors fade, leaves dry out, and plants begin preparing for the winter ahead.
As we’ve shared in previous blogs about preparing your pond for fall, seasonal pond maintenance is important, and autumn aquatic plant care is just as important. Savor the rest of the water gardening season by providing the extra attention needed to properly winterize your plants.
Why Autumn Aquatic Plant Care Matters
Taking care of aquatic plants before the first frost ensures healthier plants, cleaner water, and a more balanced ecosystem. Removing dying foliage prevents rot, while overwintering plants correctly gives them the best chance of thriving once warm weather returns.
Know Your Plant Hardiness Zone
Before making a care plan, check your USDA plant hardiness zone. These zones identify which plants can survive winter in your area, based on typical temperature lows. Plants that can survive your local winter are considered hardy. Those that cannot are non-hardy and will need extra protection or indoor care.
Caring for Hardy Aquatic Plants
Trimming and Maintaining Marginal Plants
Bog plants, hardy marginals, water lilies, and lotus are considered hardy. When temperatures drop and foliage turns yellow or brown, stop fertilizing as they prepare for dormancy. Trim marginal plant foliage down to about 2 inches above the water level and remove any decaying material so it does not sink into your pond. Rotting plant matter can harm water quality and aquatic life. A few plants, such as cattails and semi-evergreen varieties, can be left untrimmed to add visual interest in winter.
Overwintering Hardy Water Lilies
If your pond is deep enough that it 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.
Special Care for Lotus Plants
Lotus foliage should only be trimmed back after it has fully died and turned brown. Cutting green leaves exposes the hollow stems, making the plant vulnerable to disease that can damage or even kill the tuber. Lotus tubers cannot withstand freezing temperatures, so move any growing in shallow areas to deeper shelves away from ice.
How To Overwinter Non-Hardy and Tropical Plants
Bringing Tropical Marginals Indoors
In warm climates, tropical marginals will keep growing and will require fertilizer as usual. In colder regions, they will not survive outdoors and need to be moved inside for the winter. Most tropical marginals do well potted in heavy garden soil inside sealed clay pots without drainage holes. Larger containers can hold multiple plants. When kept wet, they thrive in a sunny window or sunroom, but supplemental grow lights and heated water (around 70°F) make overwintering more successful.
Caring for Floating and Submerged Plants
Plants of tropical origin, including many floating and submerged varieties, cannot survive harsh northern winters. Water gardeners in these regions should treat them as annuals or bring a few indoors to restart in spring. Since they are fast-growing, just a handful can easily repopulate your pond. Aquariums, children’s pools, or large plastic tubs make great indoor homes for these plants.
Using Supplemental Light and Heat
Tropical plants are sensitive to cold and need plenty of light and warmth to stay healthy. Provide bright lighting with a grow light or plant light, along with heated water, to ensure they make it through the winter. Avoid fertilizing them during this time.
Overwintering Tropical Water Lilies
Keeping tropical water lilies indoors over the winter is very difficult. For most water gardeners, the best option is to treat them as annuals and purchase new ones each season.
Storing Tubers Like Taro and Canna
Taro and Canna are tuber plants that can be dried and stored without water or light in a frost-free area such as a basement. Cover the top of the pot with a damp piece of burlap or newspaper to help retain moisture. The darkness encourages dormancy and prevents premature sprouting. Check on the container occasionally to ensure the potting material remains slightly moist.
Set Up Your Pond Plants for A Healthy Spring
Taking time now to prepare your aquatic plants means cleaner water, healthier plants, and a stronger pond ecosystem in the spring. Whether you’re trimming hardy marginals, sinking lotus, or overwintering Tropicals indoors, these small steps will make a big difference for your water garden.