6 Simple Steps to Get Your Backyard Pond Ready for Winter

While backyard koi ponds provide a tropical oasis in the warmer months, they go dormant in winter in most parts of the country. With a little extra prep work, you can ensure the health of your fish and aquatic plants through this challenging period of cold temperatures. Aquatic biologist Trevor Henderson of The Pond Guy explains how to best prepare your water garden or pond for the winter elements.

Trevor Henderson is an aquatic biologist and backyard pond expert for online pond-supply retailer The Pond Guy.

1. Remove Leaves

Leaves in your pond can clog filters and suffocate fish, a problem that's especially heightened from fall into winter. During this season of heavy foliage drop, skim or net falling leaves often. If many trees surround your pond, consider buying a domed net that goes over the water to keep leaves from accumulating on the surface.

2. Disconnect Water Filter and Pump

Just before temperatures reach freezing, disconnect your pond's water filter and pump to avoid damage "We want to avoid any ice accumulation when temperatures reach freezing," says Henderson.

Clean filters thoroughly, then store them indoors. Pumps should be cleaned and then stored inside a five-gallon bucket of water indoors, says Henderson, to keep the gaskets and seals hydrated (reducing the chance of cracking). "Technically, some models do not require this, but since it does not hurt any of them and only helps most of them, it is easier to just recommend doing it as a blanket statement," he says.

If you're in an area where the water doesn't freeze in winter, then you can leave the filter and pump running throughout the season. "They will not need to be cleaned nearly as often, as cooler weather slows down the metabolism of everything," says Henderson.

3. Move Plants

Part of the beauty of a backyard pond are the aquatic plants in and around it. Most will not survive the winter in place, however. If you've placed nonhardy potted plants like elephant ears around the pond, you can easily move those indoors (giving your home a welcome tropical touch in the process).

Some hardy water lilies, lotus, and submerged plants should survive the winter if your pond doesn't freeze solid. To help them survive, trim their foliage and then move them to the deepest area of the pond. In colder winter zones, you'll need to treat these plants like annuals, removing and replanting them from year to year.

4. Discontinue Algae Treatments

Pond owners typically apply some kind of treatment to the water to keep algae at bay through the warmer months. In winter, however, these treatments are not effective and can even be harmful to fish. Once outdoor temperatures regularly dip below 50°F, stop using algaecides, with a plan to resume use in the spring.

5. Stop Feeding Fish

As outdoor temperatures decline, koi's metabolism slows, making them unable to digest food. It can be dangerous and even kill koi to continue feeding them throughout the season. Henderson's suggestion for slowly preparing koi for winter: "Move to a wheat-germ based food when water temperatures are between 50 and 40 degrees," he says. "Below 40 degrees most fish do not require additional feeding throughout the winter."

6. Prepare for Icy Conditions

Yes, koi can survive even the chilliest winter, provided you create the right conditions in your pond. Aeration is required to ensure your fish remain healthy during hibernation. Throughout winter, it's critical to install a de-icer (sometimes called a pond heater) to ensure an area of open water for the fish to get oxygen. "It is not heating the entire pond, just keeping a small hole open in the ice to allow for gas exchange," says Henderson.

"Most are thermo-regulated so you can install them at any time, and they will only turn on and off as needed," he adds. There's no one-size-fits-all de-icer. To figure out which one is best for you, "check your zone and pond size against the manufacturers' recommendations for what wattage heater you need," he says.