Winterizing a pond is less about one big shutdown and more about preparing the system for cold, ice, and a slower season. Start early, work through the pond in order, and choose the running or shutdown approach that fits your climate and equipment.
Winter puts several kinds of pressure on a pond. Ice can limit gas exchange, decaying organic matter can add unwanted gases, and ice dams in waterfalls or streams can redirect water and cause loss over the edge. A running system can also lose water to evaporation. The steps below address those risks one by one.
1. Install Pond Netting Before the Leaves Fall
Put pond netting in place before the heaviest leaf drop. It catches leaves before they sink, which makes the later cleanup much easier. Use Aquascape Protective Pond Netting as directed for a reusable barrier over the pond and waterfall. Once most leaves are down, remove the net, clear the debris, and store it for next season.
2. Remove Leaves and Debris
If leaves have already reached the pond, skim the surface and remove settled material from the bottom. Organic matter left in the pond breaks down through winter and adds to the cleanup waiting for you in spring. Work carefully around plants, drains, and circulation points so debris does not get pushed deeper into the system.
3. Keep the Skimmer Clear
Check the skimmer basket frequently while leaves are still falling. Emptying it before flow slows helps protect circulation and prevents a small pile of debris from becoming a blocked intake. Once the leaf drop is over, the checks can be less frequent, but the basket should still be clear before sustained freezing weather.
4. Trim Dead Foliage
Cut back dead or dying marginal growth so it does not become additional organic material in the water. Hardy marginal plants can usually remain in the pond after trimming. Remove tropical plants according to their care requirements, and keep plant debris out of the pond and skimmer.
5. Prepare Waterlilies for Cold Weather
Trim hardy waterlilies as appropriate for the variety and move the containers to a deeper part of the pond when the plant’s care guidance calls for it. Tropical waterlilies need a different winter plan and may need to be removed. Follow the plant’s own label or care instructions rather than applying one depth or trimming rule to every waterlily.
6. Support Water Quality Before Winter
Beneficial bacteria can help process organic material that remains after fall cleanup. Choose a product whose temperature range and instructions fit your pond, and follow that product’s label. The goal is to enter winter with less decaying material and a system that is easier to manage when cold weather slows biological activity.
7. If You Keep the Pond Running
A running pond or waterfall can stay attractive through winter, but it needs regular checks. Watch the water level, top off for evaporation when appropriate, and look for ice dams that redirect water over the edge. During severe cold, monitor whether the surface is sealing over and whether the pond still has a reliable path for gas exchange. A small recirculating pump, such as the AquaForce® Solids-Handling Pond Pump, may be part of a running setup when selected and used for the pond’s design and conditions.
8. If You Shut the Pond Down
For a seasonal shutdown, remove and store the pump according to its instructions, drain exposed plumbing so standing water cannot freeze and expand, and clean and store filter media where it will not freeze. Keep gas exchange in mind after shutdown. A pond de-icer can help maintain an opening during freezing weather: the Aquascape 300 Watt Pond De-Icer is listed for that purpose and should be used according to its instructions and your local conditions.
9. Adjust Fish Feeding Before the Water Gets Cold
As water cools, fish digestion slows. Feed less often and in smaller amounts during the transition, and remove anything they do not finish promptly. PondScape Cold Water Koi and Goldfish Food is a wheat-based option listed for colder periods. Stop feeding when the water falls below 50°F, following the project’s established temperature guidance rather than the calendar.
Can Koi Stay Outdoors Over Winter?
Often, yes, when the pond’s design, depth, climate, oxygenation, and gas exchange are suitable. Around two feet of depth is a common example in very cold regions, but the right depth depends on your climate and pond design, not a universal rule. Leaving hardy fish outdoors keeps them in familiar habitat and avoids the stress of handling. The tradeoffs are that oxygen and trapped gases need managing, predators remain a risk, and it is harder to see how each fish is doing. In extreme climates, or in a pond that cannot keep an open hole in the ice, bring sensitive fish indoors or seek advice suited to your situation.
Related reads: More Tips for Winter covers caring for a pond that keeps running all season, and Does Your Pond Need a Koi Pond Aeration System? explains when aeration helps and what a system can and cannot do. Browse the PondScape Learning Center for more pond care guides.