Preparing Your Pond for Winter

Preparing your pond for winter may involve a variety of tasks. Some of these are relevant for any type of pond some are more specific. Now, don’t know about you, but I do find check lists helpful when carrying out gardening tasks that only need doing once or twice a year. This article is a check list for you, so that the basics of making your pond winter ready are covered.

Firstly, an obvious but important fact to determine – what pond or ponds do you have in your garden?

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

The tips given here relate in the main to smaller domestic ponds; as, for example, swimming ponds have their own requirements.

NB For those with koi carp in their pond, I am presuming that you already have a specific cleaning regime in place.

Health and safety note – If you’re planning to carry the tasks out by yourself, it may be advisable to suggest that there is someone at least keeping an eye on what you get up to. After all, even adults can drown in 4” of water.

Preparing Your Pond for Winter – 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.

It is natural for still ponds to silt up and turn into 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.

And moving onto a few specific tasks and tips for preparing your pond for winter –

Plants – in and out the Pond

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 the net, shake out leaves and replace net for the next windy day’s offering. (Theoretically) Leaves and foliage should not be left to rot in the pond, as decomposition uses up the oxygen in the pond water.

Unless there are only 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. Evergreen plants will lose leaves year round, so are a continuous task to remove from the pond.

Take this opportunity to check over your pond plants, dividing clumps of waterlilies, for example, and refreshing aquatic soil in the submerged pots.

Preparing your pond for winter includes the area immediately adjacent to it, which may be a semi-submerged shelf for marginal plants, a bog garden. Many gardeners like to have a border next their pond planted with wildlife friendly plants. These deciduous marginal plants should generally have foliage cut back to prevent it form being blown into the pond. You may however, like to leave seed heads in situ to provide food for wildlife. Where possible, there should 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, either by yourself or sent away for a service. They may be replaced in the pond if used over winter, or if not needed, then stored in a frost free shed or garage.

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. Not least to prevent unwanted leaks.

Where the fabric can be seen, this is a fairly easy job. Then you realise 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.

Are you able to carry out repairs yourself or is greater expertise needed? For example, small splits in an otherwise ‘healthy’ liner will be simple, as would surface cracks in external render.

Preparing Your Pond for Winter – 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, pond scoops for scooping out vegetation and silt
pond vacuum for larger ponds can help cut down on time (these can be hired)
trugs and buckets for plants, silt
pond liner brush for cleaning butyl liners
tarpaulins to lay next to pond for containing 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 to prevent accidents.

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. Unwanted plants can be disposed of dispose of 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).

This is likely to be the smelly part of the job, especially if the pond hasn’t cleaned out for some time!

Pond Water

One of the tasks for preparing your pond for winter is to check the water quality as even the best filtered pond can accumulate unwanted chemicals. Nitrates in particular, are detrimental to fish and other pond life. It is easy to check using a simple nitrate test kit from a specialist store, garden centre or online.

Fill up the pond level with rain water rather than using tap water. This has chlorine and other chemicals added to it, which are also not good for the pond ecosystem. If you can plan ahead, and the weather is being helpful, leave trugs and buckets out when it rains. You’ll invariably need more water than you expect to refill a pond!

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.

If you would like help with learning more about your garden and gardening, why not ask about our bespoke Gardening Lessons, where your classroom is actually your own garden. We can help you learn gardening basics, carry out worm and other experiments and also show you how to plan an ornamental border or kitchen garden.

And for further gardening advice and inspiration, check out Plews Potting Shed blogs, including the selection below and our monthly Tipsheet – You could come and find us on Instagram Pinterest and Facebook too.