As it gets colder your pond plants will start to collapse at the start of Autumn. Frightening really that summer has been and gone so quickly!
As waterlily leaves begin to turn brown remove them from the pond so that they do not sink to the bottom and rot away under water over winter. In more Northerly areas it will soon be time to remove any annual floating plants that will turn black in the first frosts and begin to decay in the pond water.
British Native Frogbit (Hydrocharis morsus-ranae) is starting to breakdown now and the dormant buds will drop off the leaves and fall to the base of the pond. These are 5x10mm or 1/8" x 1/4" and look like apple pips. These will be easily lost if you do not remove some now while you can still see them and put them in a bucket until after you have finished your Autumn maintenance in November.
Water Soldiers (British Native) will also begin to sink below the water surface to avoid the frost and ice over Winter. These can be allowed to fall as they will be obvious when you clean sludge from the pond base later and are not at risk of being thrown out by accident.
Neither of these British Natives are available in our Shop now and will not be available for sale again until May/June next year.
Sagittaria sagittifolia will now be looking yellow leaved and over. This is the time to find the bulbils in the mud of the pond and replace them in the baskets. The parent plant will die back after a couple of years but the new plants do not grow from the centre of the old basket but from the bulbs that can set down 6-8" away from the original basket.
Continue to try and remove any duckweed you have so that it does not seed down onto the bottom of the pond only to reappear next Spring.
Be prepared with the net to cover the pond - tree leaves will soon start to fall and the net should be across the pond to prevent them falling into the water - sinking and then rotting down over Winter. Put the net in place as soon as the first winds are forecast - the first windy night will bring down more leaves than you expect and you will have the job of having to remove them all by hand.
Net earlier rather than later to avoid extra work! Some tree leaves take a long time to rot away and use up a lot of oxygen in the process.