Take a break, it’s cold outside.
By early December there’s not much else left to do with your garden pond except wait for spring. If you didn’t cover your pond with a net to keep leaves out by early November then it’s too late now, and the leaves will have to overwinter in the pond. Perhaps the only decision to be made until March is whether you should keep the pump running or turn it off. First, a bit of background.
I have six ponds in my one+ acre garden in Warrenton Virginia, and I supervise the installation of more than a hundred ponds each year through Meadows Farms Landscape Department. Please visit our website MeadowsFarms.com for much more pond and gardening information.
I keep most of my ponds running through the winter because I like the way they look throughout the year, and running the waterfall insures that ice will not cover the pond, so I don’t have to worry about my fish. Customers seem most worried whether running the pond with freezing temperatures will harm their pump. In the mid Atlantic region this should never be a problem. All the plumbing in my ponds are flexible PVC which is more resistant to freezing than regular PVC pipe, but any pipe should be fine as long as water is moving. If the electricity goes out, all bets are off.
For some people this potential problem might be enough of a reason to winterize the pond and turn the pump off, but I’ve had ponds for almost 20 years, and it’s never been a problem for me. If you decide to turn the pump off then it’s probably a good idea to pull submersible pumps out of the pond. It is possible that ice could form around the pump and potentially damage it. I’ve had times when I’ve turned pumps off for a period through the winter, and I’ve left the pumps in the pond, but I tend to do everything with the least amount of effort required. Anyway, I’ve never had a problem leaving the pump in the pond.
Surface ice and fish
Just about the only reason to worry about ice forming on your pond is if you have fish. Everyone in the pond business has stories, or has heard stories, of fish surviving when they were frozen solid in the ice. I haven’t knowingly done this, but I’ve let the ice on a pond that was turned off linger longer than I should have, and fish have survived. And other times they’ve died.
It seems a shame to spend your hard earned money, and enjoy the experience of watching as your fish grow, only to wipe them out in a week or two. It’s quite simple, either keep the pump running, or take some other measure to keep to keep some small part of the surface of the pond free of ice. When I turn a pond off I put a thermostatically controlled “pond heater” in to keep a small hole open. The heater doesn’t heat the pond, except for an areas the size of a salad plate.
It’s especially important to keep a surface hole open if you didn’t get your pond covered in November and the pond is half filled with leaves. This will be a mucky chore to clean in March, but the immediate concern is that if the pond becomes ice covered the nasty gases from the decaying leaves can’t escape and will harm your fish. So, keep a hole open, and all will be well until spring.
Waterfall ice dams
About every two or three years we seem to have a cold stretch that lasts for a week or more. Even with moving water the open area in the pond will get smaller each day. The waterfall will begin to freeze after a couple days and, although water is flowing over it, the ice get thicker each day. At some point the ice may become thick enough that the water flowing over it flows right out over the edges of the pond. In particular, in areas with streams this can happen in just a couple days, and is hardly notiecable until the pump runs dry.
If this happens, you can turn the pump off and wait for it to thaw, but if you have fish you’d better make plans to prevent the pond from freezing completely over. I can tell you that ice that takes a couple days to form can takes weeks to melt. If you don’t have a pond heater I’d recommend ordering one just in case. I’ve been able to set the heater directly on top of ice, and it will thaw its way down through. Don’t bang on the ice to break a hole through! And if you make a hole with a hot pot or boiling water, how are you going to keep the hole open? I’m sure there are ingenius low-budget way of doing this, but I’ve found that the pond heater is a relatively low cost appliance that last year after year.
Forget about them. The only harm you can do to your fish is to feed them.
Once the water gets cold your fish are headed to the warmer bottom. Every once in a while we’ll get a warm spell and the fish will come up to sun-warmed surface looking to feed. Resist the temptation, and let them go hungry for another month or two. It’s much better to err on the side of feeding too late rather than too early. Too early and your fish die, too late and nothing happens.