Ponds may be –
- large or small
- formal or informal
- with or without fish
- a wildlife pond
- with or without plants
- still water or have a fountain
- a swimming pond
- concrete, butyl lined, or puddled
- raised or sunk
There are a variety of tasks required for getting all of these ponds ready for winter and there are some overlaps as well as specifics. This article is a check list so that the basics are covered.
NB For those with koi carp in their pond, I am presuming that there is already a specific cleaning regime in place.
Depending on the size of garden and staff, there should be guidelines regarding safe working conditions in and around ponds. If you are the only gardener, it may be advisable to suggest that this task requires extra labour brought in. Even adults can drown in 4” of water.
General Points
Autumn is generally a good time to clean out a garden pond, as any young newts, frogs and toads will have left and the water level is likely to be at its lowest after the warm summer.
However, there are reasons why a major overhaul on certain types of pond is not recommended in the autumn. For example, waterlilies may rot if they are damaged and fish die overwinter if their scales are knocked off. In autumn.
It is natural for still ponds to silt up and turn in to bog gardens. In the wild this would happen, with new ponds developing to replace old. In a garden situation, ponds need to be cleaned out every three years or so to prevent this from happening.
Ponds do not have to be ‘official’ wildlife ponds in order to have a delicate ecosystem, so it is best to avoid extreme changes in the quantity of plants and vegetation in the water wherever possible. In order to leave a safe habitat for pond wildlife, a good rule of thumb is to remove no more than half the vegetation and plants at a time.
Leaves
If there is a net in place on the water surface then most of the falling leaves should be caught in this. Theoretically this makes it an easy job to lift off net, shake out leaves and replace net for the next windy day’s offering.
Leaves and foliage should not be left to rot in the pond, as decomposition uses up the oxygen in the pond water.
Plants
Unless these are evergreen plants, they will be dying back. Deciduous foliage should be cut back, ideally before it falls into the water. The stems can be taken down to nearly the base.
Take this opportunity to check over your pond plants, dividing clumps of waterlilies, for example, and refreshing aquatic soil in the submerged pots.
Deciduous marginal plants should generally have foliage cut back for the same reason, although leaving seed heads in situ provides food for wildlife. There should always be some evergreen cover for small creatures around informal and wildlife ponds.
Moving parts
Both plant and fish activity slows down as the temperature falls and daylight hours shorten. This means that the pumps and filters that have helped keep the pond a balanced and healthy environment throughout the spring and summer can have their flow reduced accordingly.
By late autumn, the mean water temperature is likely to be around 10 degrees C, so the ultra violet sterilisers and pumps can safely be switched off and filters disconnected.
These can then all be cleaned out and checked; guidelines may require a designated staff member to complete this task.
They may be replaced if used over winter or stored in a frost free shed or wherever their assigned winter storage place is.
Pond walls
Whether the pond is a sunken pond with a liner or a raised concrete and rendered pond, an annual check is a minimum maintenance requirement.
Where the fabric can be seen, this is a fairly easy job – until it is realised that even raised ponds have an inside. Checking over the inside liner wall is easier if it is possible to drain at least some of the water out. Some concrete ponds and pre-fabricated liners have drains for this purpose. If not, then buckets may be the order of the day.
Decisions on whether it is possible to carry out repairs inhouse or whether more expertise is needed may have to be made. For example, small splits in an otherwise ‘healthy’ liner will be simple, as would surface cracks in external render.
Cleaning
What equipment will be needed? That does partly depend on the size of the pond, but items could include: –
- nets of various sizes, some come with telescopic poles
- pond weed brush, soft plastic lawn rake and pond scoops for scooping out vegetation and silt
- pond vacuum for larger ponds can help cut down on time
- pond liner brush for cleaning butyl liners
- trugs and buckets for plants, silt, and so on
- tarpaulins to lay next to pond to contain some of the mess
- for humans, as a minimum, pond gloves and wellingtons; waders for deeper ponds
If the pond is a large one or particularly deep, other items will be required, such as ropes or a small boat. Safety measures should be in place and procedures followed.
Last but not least, you’ll need a camera. Or rather someone else will need a camera, so that they can take a photo of you falling into the pond…But seriously, taking photos during the job will, for example, allow you to compare the condition of a pond liner with the previous year.
Begin by removing pond weed and any floating dead vegetation. Leave these on the pond edges so that creatures can crawl back in to the water before you dispose of the unwanted plants on the compost heap.
Scoop out excess silt from the bottom of the pond, leaving about 2” / 5 cm in situ. Keep a bucketful of silt to one side to re-introduce tiny but essential organisms into the pond. The remainder can be used as a fertiliser in the garden as it’s full of nutrients. It may need to be further composted before use, and ensure that this use is allowed.
This is likely to be the smelly part of the job, especially if the pond hasn’t cleaned out for some time!
Water
One of the autumn pond tasks is to check the water quality – even the best filtered pond can accumulate unwanted chemicals. Nitrates in particular, are detrimental to fish and other pond life and it is easy to check using a simple nitrate test kit.
Then fill up the pond level with rain water rather than using tap water which has chlorine and other chemicals added to it which are also not good for the pond ecosystem.
Lastly, a final health and safety point for when all the equipment has been cleaned and put away in the correct places. Thoroughly wash hands before eating the homemade cake.
Marie Shallcross
Plews Garden Design and Consultancy