Your Winter Wildlife Pond

Winter approaches and our gardens need careful thought at this time, if we are to avoid creating too much disturbance to over-wintering wildlife.  Many of the beneficial creatures that we encourage to gardens and allotments through the spring and summer must find shelter until the warmer weather returns.  Hedgehogs build leafy winter hibernation nests, butterfly larvae pupate or adults find cool dark places to sit out the frosty weather and ladybirds search for shelter from the cold in cracks in bark, in log piles, deep in tufted grassy vegetation, hollow flower stems or in the foliage of conifers.  Some creatures go about their business as usual, particularly the smaller mammals such as mice and shrews: our native wildlife has a variety of strategies for surviving the winter.

All this means that winter gardening is full of hazards – tidying shrubs may expose hibernating insects or reduce roosting places for small birds, and cleaning up borders removes valuable dead vegetation where many insects, especially ladybirds and lacewings, find shelter.  There is one garden habitat that may well be in need of work at this time though – the wildlife pond is at its least active now and a little work at this time can ensure that it is in tip top condition come next spring.

Autumn seems to be arriving later and later, so your first task is to deal with excess leaves that may still be falling.  A few dead tree or shrub leaves finding their way into your pond is no great problem as long as it is not completely iced over for any length of time throughout the winter.  Leaves break down and create a substrate at the bottom of the pond that many small animals use for finding food, shelter and for breeding.  Frogs too sometimes spend the winter deep in the squidgy mud in the depths of a pond so at least some of this substrate is vital to your pond wildlife.  Large quantities of leaves however, especially species such as beech that are particularly tough, contain tannins, and break down slowly, can cause a build up of potentially toxic gasses.  So a little time spent removing excess leaves is time well spent.

Although a good covering of plants is essential for wildlife, it is important to start the spring with a fair proportion of open water.  Wildlife experts recommend that a minimum of one third of a pond surface should be open and accessible to flying insects such as dragonflies and water beetles.  These animals search for new habitats from an aerial perspective – the glint of open water can be spotted by a dragonfly from some height.  This means that your pond stands a better chance of attracting new species of insect if the water is visible from above.  Frogs and toads tend to need space for mating and egg laying, and will often choose open water for these activities rather than densely covered water.  This means that at least some vegetation can be carefully removed at this time of year, especially any species that proliferate rapidly.  Water soldier, if it likes your pond, can produce its vegetative offspring, initially attached to the parent plant, at an alarming rate.  However these plants are easily removed as they are free floating and not firmly anchored to soil in the bottom of the pond.  A rake handled with care and avoiding the pond liner, can be used to gently trap these spiky floating plants and manoeuvre them to within easy reach.  Bogbean too can become a problem, albeit an attractive one.  Its spreading stems will rapidly move across the surface of the pond, obscuring the open water.  The best implement for this plant is a long handled pruner.  A quick snip of the stem near the water’s edge will deal with it, and it can then be caught with a rake and brought ashore.  A pruner that also holds onto the cutting is especially useful here.

Other more difficult to control plants should be thinned out now but this may be easier said than done.  Rapidly growing marginals such as burr reed, sweet galingale and some sedges and irises can be difficult to control and are best left out of a new small pond.  If you already have them you have no alternative but to move in with a heavy handed approach and do your best to uproot those that are surplus to requirements.  Again, take as much care as you can to avoid tearing the liner – these can be repaired but it is best to leave any plant that you suspect may have rooted through.  Oxygenators can also be thinned out this month, but bear in mind that they are the life blood of a wildlife pond and some pond experts would say that you can’t have too many!  All plants removed from a wildlife pond should be left on the pond side for a few days to allow creatures to find their own way back to the safety of the water.

Alien invaders can also be dealt with at his time.  New Zealand pygmyweed, otherwise known as New Zealand stonecrop (Crassula helmsii) is a serious problem in our native waterways.  Sadly lots of garden ponds seem to have this invasive plant now and it must be dealt with whenever possible to prevent it taking over completely and shading the water to the extent that wildlife no longer thrives.  The best that we can do at present is remove it by hand as thoroughly as possible, taking into account that it will be an ongoing problem.  Research continues into the treatment of this persistent thug, but as yet there is no solution to the problem.  Parrots feather (Myriophyllum) is another invasive plant though less problematic than Crassula and easier to remove.  Both of these species should be allowed to dry out thoroughly before composting, and never disposed of in green waste bags, left in the countryside, or given to friends.

Once these tidying tasks have been completed one more creative job can be undertaken.  If you have small plants or plugs of suitable wetland plants available, these can still be added to spaces in marshy pond borders or planted on pond ledges – a good opportunity to add new species to a wildlife pond.  Native wildflowers will be relatively dormant now and will come to no harm through the winter months.  Planting now will give them an opportunity to settle and get ahead in the spring.

As the winter progresses we have no knowledge of what the months ahead will bring.  Prolonged periods of frost, snow and ice seem to be things of the past for many of us, but keeping our ponds free of surface ice is still an important task.  Make sure that you check your pond on a regular basis on colder days.  If continuous ice is still present after midday, a ‘breathing’ hole should be made in order to prevent the build up of any gases beneath the ice surface.  This is most effectively done with the base of a metal saucepan, full of very hot water.  Simply rest the saucepan on the frozen surface until a hole is gently melted through.  In very icy conditions your pond may not provide easily accessible drinking water for local birds so try to ensure that water is available to them in an additional container of some sort.

The next couple of months can be frustrating if you are a restless gardener but keeping an eye on your garden wildlife residents and visitors and ensuring they have what they need may well satisfy that gardening urge until the weather warms again.


© Text and photographs Jenny Steel 2017