It is our belief that the less you do manually to a pond the better; however, there is a minimum amount of autumn maintenance that needs to be done before the winter hibernation starts. Cut back any dead foliage from deep water plants such as lilies, emergent plants such as rushes and reeds and marginal plants such as Iris and Marsh Marigolds. Re-pot or divide any overgrown marginal plants every two to three years.
Those Falling Leaves
Although surrounding trees give much needed shade in the summer, the downside is that their leaves fall into the pond in autumn. If it is practical to net the pond at this time of year it will go a long way toward reducing the amount of sludge that the leaves will turn into as they decompose. A small amount of sludge is beneficial as it contains eggs, grubs and insect larvae, but an excess of sludge will only encourage blanket weed to thrive.
Repair that leak
If your pond has sprung a leak, you will have no alternative but to drain the pond, repair the leak and refill the pond. Try to save the pond water as it contains beneficial life. If you do need to top-up with tap water, do add a water conditioner to remove harmful chlorine. Products for this purpose are available from most Aquatic Centres and a top-up dose of Aquaplancton will help to re-balance the pond after such a major upheaval.
Always do any autumn maintenance before the winter hibernation starts. Frogs will return to the pond in autumn to see out the winter. Oxygen levels will rise as the water temperature drops. Once the water temperature falls to 45 degrees Fahrenheit (7.2 degrees Celsius) fish will hibernate on the bottom of the pond.
We all have a tendency to over feed our fish, we mean well, but fish continue producing excrement, even when they are hibernating, so it’s good to keep this fouling of the water to a minimum. If your fish do come to the surface during hibernation it will only be for oxygen, so do resist the urge to feed them.