Preparing Your Pond for WinterWith autumn slipping into winter the pond enters a state of suspended animation as the water cools and the metabolism of fish and plant life slows right down. At this time of year, a few last jobs remain to be done to prepare the pond for the colder months ahead and to ensure that its inhabitants will over-winter successfully and have the best possible chance of a good start when things warm up again the following spring. Year round pond maintenance is important, and we have guides for Spring. Autumn, Summer and Winter

Plant Protection

Now is a good time for a final clean up, to remove any leaves which may have found their way under the net cover, or any dead plant foliage which was missed during autumn pruning. Leaving excess organic matter in the pond over the winter can harm the water quality, which is why some pond-keepers recommend using this opportunity to do a partial water change and remove some of the sludge from the base of the pond. This material is made up of a mixture of decaying plant matter, fish waste and other material which has sunk to the bottom and its gradual decomposition will add significant quantities of nitrates to the water, over time.

By the onset of winter, any frost-sensitive pond and bog plants should already have been protected or removed as appropriate and hardy water lilies lowered into the deeper reaches of the pond, the non-hardy varieties being covered and stored somewhere cool, but frost-free. It is also the time to transplant lilies, if desired – cutting off the leaves and stalks to leave the buds and shortening the rhizomes by around a third.

Fish Factors

Having been winding down the feeding of fish and moving to a low protein diet as autumn progressed, once the water temperature reaches 10–12 degrees C, a good quality wheatgerm-based food – available in stick or pellet form – should be used until winter finally grips. At around 7 degrees C, fish naturally stop eating and drift into a state of semi-hibernation. At this time, the fish tend to retreat to the deeper portions of the pond, where during winter, the water is warmer – and the deeper the pond, the more noticeable this temperature effect. To avoid disturbing the warm layer that they are languishing in, it is a good idea to take steps to reduce the pond re-circulation which will tend to mix in colder surface water. Some pond-keepers choose to switch off their pumps, often removing them for routine maintenance, while others favour decreasing their flow rate and relocating them away from the deeper reaches.

In the same way as the fish slow down for winter, at around 10 degrees C and below, the biological activity in the filter is also much reduced – so switching off the pump is not quite so drastic a step as it might seem. However, before doing so, it is as well to check the manufacturer’s instructions, since some kinds of pumps must be removed and re-greased if they are not to be run for any length of time. With no real need of filtration throughout the winter, this is an ideal chance to disconnect and drain the bio-filter, strip it down and clean it thoroughly, storing it – along with the pond’s UV clarifier – in a safe, dry place until it is needed again.

In bad winters, ponds in some areas of the country may be prone to be iced over for prolonged periods. This is not ideal for any fish they contain, since an enveloping cover of ice stops the natural exchange of gases at the surface, trapping carbon dioxide and others in, while keeping oxygen out. There are various solutions, from small electric heaters to floating something on the surface, the idea being that its gentle movement breaks up the ice as it forms, stopping a complete layer forming. Opinions vary as to whether a bobbing football really works – but the plastic ducks some pond-keepers use certainly make the pond look cheery!

A final point to consider is adding a net over the pond if it does not already have one – at this time of year to keep out cats or herons rather than leaves. In their semi-torpor and made more conspicuous by the lack of vegetation in the pond, fish make easy targets for passing predators, so it can sometimes be a good idea to give them a bit of added protection.

Winter in the pond is something of a dead time, when plants, fish and other creatures have done their growing and breeding for one year and now must simply survive the cold to start all over again in the next. While this enforced dormancy may offer little spectacle to captivate the water-gardener, it is never-the-less an essential part of the cycle and with a little bit of care and attention as the days draw in, we can be sure that the pond and its inhabitants are up to the challenge.

Reducing Food Frequency

As the temperature drops, gradually reduce the amount of food you feed your fish. Once the temperature falls below 50°F, stop feeding your fish altogether.

Fish have a slower metabolism in colder temperatures, so they require less food. Overfeeding your fish in colder temperatures can lead to digestive problems, which can be fatal for your fish. Gradually reducing the amount of food you feed your fish as the temperature drops will help them adjust to the changing conditions. Once the temperature falls below 50°F, their metabolism will slow down significantly, and they will require very little food to survive. It’s important to stop feeding your fish altogether once the temperature reaches this point to prevent any health issues.

Protect tender plants from the cold

If you have plants in your pond, they will also need to be protected from the cold. Hardy water lilies can be trimmed back and placed at the bottom of the pond to overwinter. Other plants, such as tropical plants or marginal plants, will need to be removed and overwintered indoors or discarded.

Different types of pond plants have different cold tolerance levels. Hardy water lilies can survive the winter by trimming back their leaves and placing them at the bottom of the pond. This will help protect them from freezing temperatures. Tropical plants and marginal plants, on the other hand, are not cold-tolerant and will need to be removed and overwintered indoors or discarded. It’s important to research the cold tolerance of your specific plants and take appropriate measures to protect them during the winter months.

Clean pumps and filters

Before shutting down your pond pump and filter, be sure to clean them thoroughly. This will help prevent any buildup of organic matter or debris, which can lead to water quality issues in the spring.

Cleaning your pond pump and filter before shutting them down for the winter is essential to prevent any buildup of organic matter or debris. This buildup can lead to water quality issues in the spring, which can be harmful to your fish and plants. Cleaning your pump and filter involves removing any debris and buildup, cleaning the filter media, and ensuring that the impeller is free of any obstructions.

Correctly position de icer

If you are using a de-icer to keep your pond from freezing over completely, be sure to position it correctly. A de-icer should be placed near the surface of the water, but not so close that it creates a hot spot. This can cause the water to become stratified, which can be harmful to your fish.

De-icers are a popular way to prevent ponds from freezing over completely during the winter months. However, it’s important to position them correctly to ensure they are effective and safe. De-icers should be placed near the surface of the water, but not so close that they create a hot spot. This can cause the water to become stratified, which can be harmful to your fish. It’s important to follow the manufacturer’s instructions when using a de-icer and to regularly check on your pond to ensure it is working properly.

Keep the waterfall running if you can

If you have a waterfall or stream in your pond, be sure to keep it running during the winter months. Moving water is less likely to freeze than still water, and the sound of the waterfall can help prevent your pond from becoming completely still and stagnant.

Waterfalls and streams in your pond can provide aeration and help prevent the water from freezing over completely. The movement of water is less likely to freeze than still water, and the sound of the waterfall can also help prevent your pond from becoming completely still and stagnant. It’s important to keep an eye on your waterfall or stream during the winter months to ensure that it is working properly and to make any necessary adjustments.

Last Modified: April 6, 2023