Winter pond care includes keeping your fish and plants safe during cold weather and freezing temperatures. I’ll show you everything needed for fall, winter, and spring.
Whether you are building an inground or above-ground pond, the basics are the same. If you are just getting started, see the complete guide to building a backyard pond.
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I live in southwestern Ontario, Canada where winter temperatures dip to around -20°C (-5°F).
When I got my first pond, I kept hearing that there was no way I could keep the fish alive (and happy) all year round in a cold climate in a pond that was less than 2-feet deep. Thankfully, that was not correct.
The basic principle for winter pond care is, as long as the water is circulating and there is an air hole to allow oxygen in and gases out, fish and plants should be fine.
It doesn’t matter how deep the pond is, it just matters that the water is moving and not frozen.
You also want to be sure the fish can go deep enough to avoid the hands of winter predators like raccoons.
The fish we’re talking about are cold water fish such as goldfish, shubunkins, and koi. You would not keep tropical fish in a garden pond in a cold climate.
If you are in a much colder climate than I am, I’m guessing it would require quite a lot of power (energy) to keep a large pond running throughout the winter, but it does not take much in a moderate cold climate like mine.
I know pond companies recommend a lot of additional products (chemicals, activated pond carbon, beneficial bacteria, and accessories like covers) but I have never used any in my twenty years of pond care so I have no recommendations to offer.
In the Fall
1. Clean Up and Lower Potted Pond Plants
Hardy plants (not tropical) and cold water fish can survive in a cold pond so long as they don’t freeze.
Tropical aquatic plants should be removed and stored indoors.
It’s also time to remove any debris including dead and decaying plants and leaves.
2. Set Up Winter Pump
A recirculating pump will keep the water moving, preventing it from freezing up.
I sit my winter pump about two feet below the surface and attach a short length of pipe to aim the water output upwards.
You could also use an aerator like this one to keep the water moving.
Whatever you use, be sure the specific one you are choosing will function in colder temperatures.
On warmer, sunny days, the fish may be more active near the surface.
3. Stop Feeding Fish
Cold water fish start to slow down and rest lower down in the pond (where it’s warmer) once water temperatures are consistently below 50°F (10°C).
They appear dormant (not moving) when temperatures drop to around 39°F (4°C) or lower.
If you feed your fish, reduce amounts or stop depending on how active the fish are. Otherwise, the feed will just rot in the pond.
Personally, I do not feed my fish at any time of year, instead letting them live off the natural flora within the pond.
During the Winter
4. Have a Spare Pump Ready to Go
Buy a second recirculating pump so you have a backup in case your main pump stops working.
If the pond does start icing over, you won’t have much time to swap out pumps before your fish are in serious trouble.
5. Use a De-Icer
You can also use a floating pond heater, also called a deicer, to ensure you always have an air hole in the surface of pond, even if ice forms around it.
Pond heaters are electric-powered, floating plastic disks with heat coils inside. You may see them sold as de-icers for livestock water troughs. There are various styles.
I use de-icers (pond heaters) in both of my ponds.
You do have to watch for warm spells though: the added heat (and light) will then encourage algae growth which starts speeding up at 16°C (60°F).
But, in the cold winter weather, they are excellent for keeping a section of the pond water liquid and not frozen.
5. Check Pond Daily
Make sure the pump is running and there is always a large air hole if the surface does start freezing over.
Unhealthy gases can form under pond ice and poison the fish. Plus, the wildlife in your garden will rely on this fresh, moving water for hydration.
It’s amazing how many animals come to drink at my pond on a cold, winter day!
In the Spring
6. Remove Deicer and Restore Plants
When the risk of freezing temperatures is over:
- Raise the plants back up to their usual positions.
- Clear out any stringy algae (I used a forked hoe).
- Clean the pump filter (see my trick here for filtering pond water without chemicals).
- Bring back tropical water plants from winter storage.
The fish will take care of themselves.
Winter pond care is pretty simple. If you take care to keep the water running, your fish and hardy plants should be fine when spring returns.
~Melissa the Empress of Dirt ♛