Wildlife Pond Maintenance

Most people agree that a wildlife pond is one of the most important features you can have in an organically maintained garden.  Not only does it provide water for birds and passing mammals to drink, but encourages many other beneficial animals to the garden.  Every organic gardener knows the value of having a good population of frogs, toads and newts around, and hedgehogs and foxes take their fair share of garden pests as part of their nightly foraging.

One of the most important features of a wildlife pond is that is has plenty of vegetation to provide cover for all the creatures that use the water in one way or another, whether for the tadpoles of breeding toads, frogs, and newts, or to encourage dragonflies and damselflies which are such efficient predators of other insects.  Most good wildlife ponds have a few inches of soil over the liner, which enables the plants to spread and increase as they will, but this in itself can bring problems.  With no limitations on the amount of water available, these wetland species are inclined to grow very prolifically.  Add to this the fact that most are rooted directly into the soil and not in containers as they would be in a more ornamental pond, and it is easy to see how rampant they can become.  Great for the wildlife but inevitably some careful management is needed to prevent the pond becoming a bog garden!  This slow transformation of pond to wet soil is a perfectly natural occurrence in the wild, but in the garden we want to maintain the status quo and ensure there is open water available for wildlife at all times. 

October is one of the better months to perform the basic maintenance that any pond needs, especially one brimming over with wildlife.  At all times of year there will be problems – whenever we start to pull out plants and trample about on a pond edge we will create disturbance for the wildlife there.  But by October most frogs, toads and newts will have removed themselves to the rest of the garden and will be looking for safe damp places to spend the winter months.  Mature dragonfly larvae have hatched and the breeding cycles of many of the smaller pond creatures will be completed.  Some male frogs spend the winter months deep in the mud in the bottom of ponds, but in general they will not have yet taken up these winter quarters.  There will still be many smaller invertebrates, water beetles, the larvae of larger dragonflies that take more than one year to complete their life cycles, even the occasional undeveloped tadpole.  But with care at this time we can do some pond maintenance. 

Choose a time when you are not rushed – this can be an operation that takes a little while - and equip yourself with a large piece of light coloured plastic.  This is ideal on which to place the excess plants and the light colour makes it easier to see any larvae, snails, water fleas or beetles that have been inadvertently removed.  If your pond is small it is likely that you will able to reach the excessive growth of marginal plants by leaning in and removing by hand, but in a larger pond you may need to (very carefully) use a garden rake.  It is surprisingly easy to puncture your liner if your pond has one, even if it is covered with soil, as I know to my cost!  Try not to forget at any time that your pond is only there because of this fragile sheet of polythene or butyl.  Liners are repairable with a kit from the Garden Centre, but the hassle involved and distress to the wildlife (and you) can be considerable.  As you gently pull or rake out the excess marginal plants, lay them on your plastic sheet.  Any animals that are immediately obvious can be put straight back into the pond, but the vegetation should be left overnight to allow most things to crawl back into the water of their own accord.  If you don’t have a friend who needs these excess plants, compost them.  Never be tempted to put them into a wild wetland habitat even if they are native species.

In a well-balanced pond, oxygenators can produce excessive growth.  These can also be gently raked out now and either donated to a friend or added to the compost heap.  Some ponds have problems with alien invasive oxygenators such as parrot’s feather (Myriophyllum aquaticum) or Australian Stonecrop (Crassula helmsii).  These must be removed and destroyed.  The Crassula in particular is causing enormous problems in our native wet habitats and has threatened rare native species in many locations.  These plants can be left in a dry situation (in a garden shed for instance) to dry out completely and die off before composting.

Water lilies that have outgrown their space can be a further problem.  Their rhizomes are so vigorous and tough that they can sometimes puncture liners.  This is problem with one or two water plants including the native yellow flag iris, and the only thing here is use discretion if a plant seems to be resistant to extraction. It is also difficult to deal with a lily without emptying the pond, something that should be avoided if possible.  If the lily appears to be stuck fast to the bottom of the pond there is a good chance that it has rooted in and removing it will open up a leak.  It is probably best in these circumstances to leave well alone unless you wish to clear the pond completely and start again although there may be sections of the lily root that can be cut away carefully with secateurs to reduce its overall area.  In general a good wildlife pond should have between one third and one half of the surface covered by floating leaves, so if yours hasn’t yet reached that stage there is no harm in leaving a lily alone.

Try to work methodically, slowly moving around the pond edge, removing your excess vegetation as you go.  This approach will allow wildlife in the pond to move away from your activities.  It is also advisable to see this as a three stage process. Tackle one third of the pond area (if there is a great deal of excess growth, go for the most overgrown section first).  Repeat the process in October next year and the year after and resign yourself to carrying out the whole process in three stages.  This way your water creatures will have time to recover and will benefit from the fact there are still areas of dense vegetation for them to take refuge in.

Once you are satisfied with the progress you have made, take the opportunity to improve the surrounding environment. A wildlife pond should never be viewed as a stand-alone habitat, and logs at the pond edge dipping into the water can provide an attractive, damp environment for small frogs and toads as they leave the water in summer.  Long grass rather than a close mown edge (or flat paving) will also make a safe refuge for many emerging creatures.

The value of water to wildlife can never be underestimated and a well-balanced pond will be alive with insects and amphibians, providing food for many other creatures that come to your garden.  Looking after your pond in an informed and careful way will increase the diversity of wildlife there, and ensure you have an army of helpers to keep your garden healthy and pest free.


© Text and photographs Jenny Steel 2017