As the daylight hours begin to shorten and summer turns to autumn, there are some seasonal jobs that need to be done around the pond to prepare it for the onset of winter. Plants, fish and equipment all have their own separate requirements and it’s best to get these jobs done prior to the onset of the bad weather.

After the lush growth of the summer, the pond plants will be starting to die back preparing themselves for winter. As soon as this begins, start to remove their dead and dying leaves. This will greatly reduce the amount organic material collecting in the pond and then decaying in the water. This is an important factor for large and small ponds alike. The reduction in organic leaf litter will help to reduce next years algae growth. So, for your pond’s sake, don’t overlook the seasonal pruning.

For the same reason, any leaves falling into the pond should be removed. It might be an idea to install a fine net over the surface of the pond, this will ensuring that the majority of the falling leaves are kept out. When installing a net, it is best to raise it off the surface of the pond, so that the leaves that fall upon it are then blown off again rather than getting soggy and rotting through the submerged net. We can set up stressed wires and temporary / permanent nets and net frames if this is what you would like. A large majority of leaves enter by being blown in at ground level, so make sure all sides of the net are either pegged or weighted down to prevent this.

As the water temperature starts to drop, the fish in the pond will start to slow down. This is because they are cold blooded; this means that their metabolic rate slows and that they require fewer calories to subsist. It is recommended to begin feeding a low protein feed mixed in with the remaining summer food 50%-50% (this allows an easier transition to the winter food) until the water drops below 8°C. At this point, it is suggested that only low protein food should be fed. During the colder months, operate a “Feed-to-Need” assessment of your fish’s hunger. If the fish are swimming near the top of the water or mid water, drop a small amount of food on the surface of the pond. If the fish are interested in feeding, they will rise and consume the food. If they are not, there will only be a small amount of food to be removed from the pond if it is uneaten. If they do eat the food, apply a little more until they have had enough. If there is cold weather on it’s way keep the feeding light so that the fish have time to purge their systems prior to the water temperature dropping. One of the biggest killers of fish in the autumn/winter time is over feeding. If uneaten food drops to the bottom unseen, and the pond then freezes, this can lead to fatal water quality issues. Always remove uneaten food after 20 minutes. The fish are clearly not interested at this time.

As the pond slows down, the pumps and filters that have helped to keep the pond balanced and healthy throughout the spring and summer, are still working hard. They are picking up organic matter from rotting vegetation and stray leaves that have got into the pond. It is therefore important not to turn off the pond’s filtration equipment as this can cause many problems. You may want to slow the flow of some systems either via pump switches or valves and it might even be prudent to by-pass waterfalls. This reduces the chilling effect of the cold air upon the water. Another good measure would be to raise the pump up in the pond to about 6” (150mm) below the surface. This will allow the fish to reside in the bottom of the pond over the colder months where the warmer water settles. Do keep an eye on the pump though, as you would not want the pump to dry out or get clogged with debris. This is an excellent time to give the pump a thorough clean, inside and out. It is also worth while totally cleaning out your filtration system in readiness for the extra debris accumulated during the cold months. Please DO NOT use tap water to clean the filter as it will kill the beneficial life in the filter which helps to balance your pond throughout the season. Use only pond or rain water for cleaning as it is chlorine free. Get right into the filter and give it a thorough clean out right to the bottom. This should just about see the filter through the worst of the Autumn/winter. But if it needs doing again later...

Another issue with turning the filtration system off is that the water left inside the clarifiers and filters will expand when frozen and crack either the casing and or the delicate quartz sleeve. This can be fatal to some incorporated systems and means that the whole system will need to be replaced due to the inability of repair, leading to great expense! Most modern pumps and filters are very cost effective to run and it is therefore a false economy to switch them off over the cold months. Another good reason for leaving pumps and filters running during the Autumn/winter is to keep the pond from completely freezing over. The moving water and the low level heat generated by the working pump will help to prevent a total freezing up of the pond’s surface. As long as the water is not disturbing the fish and measures have been taken as described above, the pond equipment will happily run all winter with little intervention. No need to worry about breaking the ice or having to risk life or broken limb on frosty mornings out in the icy garden, happy in the knowledge that the pump is still running.

The final major autumn job is to check the water quality; an accumulation of nitrates can encourage an early algal bloom in the spring. If this is found to be the case or if other levels of water quality are of concern, a partial water change 25-33% should be carried out and topped back up with tap water and a suitable de-chlorinator. If you have got all of this done before the water’s temp drops to below 8°C, it is a wise precaution to add a blanket weed treatment now. Unless you have no blanket weed that is. This will ensure a smooth blanketweed free start to the following year’s season.

For any gardener, autumn is a strange time, standing between the fading glories of one growing season and the promise of the next. The water gardener is no different in this respect. There is always a slight tinge of sadness to shutting down the pond, but if we use this time wisely to carry out a little maintenance, we can be sure that come next spring, our water feature will get the best chance to shine once more.