Getting Your Pond Ready for Fall and Winter

As the weather cools down in Southern Oregon, your pond needs a little different care. Fish become less active, plants die back, and falling leaves can quickly collect in the water.

A little maintenance now helps protect your fish, keep equipment working, and make spring cleanup easier. Here’s where to start.

Keep Leaves Out of the Water

Install pond netting before leaves start piling up, and remove any that have already collected on the surface or bottom. Check your skimmer basket regularly, especially during heavy leaf fall.

Leaves left in the pond break down, consuming oxygen and adding waste to the water. Getting them out now is easier than dealing with a layer of decomposing debris later.

Trim Back Pond Plants

Remove dead leaves and spent flowers before they fall into the water. Cut back dying growth on hardy marginal plants, keeping healthy foliage intact.

For hardy waterlilies, trim dead growth a few inches above the crown and move the pot below the expected ice level.

Tropical plants need separate winter care if you want to save them. They should not be left outside to decay in the pond.

Watch the Water Temperature

Use a pond thermometer to guide feeding. A warm afternoon doesn’t necessarily mean the water has warmed enough for your fish to eat.

As water temperatures fall below 60°F, transition to a cool-water food and reduce how much you feed. Below 50°F, stop feeding. Your koi’s metabolism and digestion slow considerably in cold water, even if they still swim over when they see you.

Follow the temperature guidelines on your fish food, and avoid starting and stopping feeding based on a single warm day.

Use Treatments Made for Cold Water

Some beneficial bacteria products are formulated for lower temperatures. PondMAX CoolBIO Cold Water Bacteria Booster helps break down organic waste and supports biological filtration in water temperatures between 35°F and 60°F.

Follow the product’s dosing instructions, and do not apply while ice is present on the pond’s surface. Keep removing leaves and debris by hand as part of your regular maintenance.

Keep Aeration Running

Your fish still need oxygen through the winter, even when they’re less active. An aerator helps maintain oxygen levels and supports gas exchange, especially if you shut down your waterfall.

For winter, move the air diffuser to a shallow shelf instead of leaving it at the deepest point. This helps leave the deeper water where your fish rest less disturbed.

Check your aerator regularly throughout the season to make sure it’s operating properly.

Plan for Freezing Weather

If you live in Medford or the Rogue Valley, you may not need a de-icer during a typical winter, but keep an eye on your pond during cold snaps. For pond owners in Klamath Falls, at higher elevations, or anywhere with prolonged freezing temperatures, planning for ice is especially important.

If your pond freezes over, maintain an opening for gas exchange. An aerator can help during lighter freezes, while a pond de-icer provides additional protection when aeration alone cannot keep an opening clear.

A de-icer keeps a small opening in the ice. It does not heat the entire pond. Pond depth, fish population, and the severity of freezing conditions also affect whether your fish can safely remain outdoors. Shallow ponds need a closer look before winter.

Decide Whether to Keep Your Waterfall Running

Shutting down your waterfall isn’t automatically necessary for winter. The right choice depends on your pond’s design, equipment, and exposure to freezing temperatures.

If you leave it running, check water levels and watch for ice buildup that could redirect water out of the stream or pond. A flowing waterfall does not guarantee the pond will stay ice-free.

If you shut it down, winterize the pump and filtration according to the manufacturer’s instructions, and drain plumbing that could freeze. Keep a separate source of aeration operating for your fish.

Pay Attention to Your Fish

Slowing down as the water cools is normal. Visible sores, unusual rubbing, or difficulty breathing deserve attention before winter sets in.

Check water quality and get help identifying the cause before choosing a treatment. Don’t add parasite medication simply because winter is coming.

Not sure what your pond needs? Stop by Wishing Well in Medford. Tell us about your pond’s depth, fish, and filtration, and we’ll help you put together a winter-care plan that fits your setup.