The Perfect Garden Wildlife Pond?

We may think we can easily create a garden pond, a haven for wildlife and an aesthetic focal point to gloat over when friends come to visit. Well it is not as easy as it may seem. I have seen a few disasters in my time and had a fair share of my own.

I once tried doing it on the cheap and used a damp-proof membrane. Bright blue, like the waters in the Bay of Nice. It didn’t fit in well with the English weather. Further, it deteriorated rapidly in full sunlight. To add insult to injury I lined the inside of the pond with carpet. This was recommended in Chris Baines’ Wildlife Garden Notebook, published in 1984. It makes sense, especially if you have children, since they are not averse to puncturing the liner with a garden fork or any other sharp object that might come to hand. Herons are not uncommon perforators of pond liners either, so a carpet placed on top of the liner, as well as below, is a good idea. Alas my carpet had a garish turquoise pattern emblazoned into it. The error was placing it turquoise side uppermost. Alongside the Bay of Nice pond liner, it proved necessary to wear sunglasses every time I went into the garden. Fortunately I moved house within a year, so problem solved.

On another occasion I decided to have a raised pond, with a PVC liner supported by a box-work of pressure treated timber. This worked out quite well, since it made an attractive feature on our Romford patio. It was possible to inspect the invertebrates in close-up because of the elevated nature of the pond surface, whilst resting elbows on the plank seat that surrounded it. On this occasion I also moved within a year, but decided to take it with me to Battle in East Sussex. The new incarnation of the pond was never as good, particularly when one of its invertebrate occupants decided to bore holes into the PVC liner. Not even a little Dutch Boy could have saved the aquatic population from the suicidal tendencies of a few short sighted individuals. Mass extinction quickly followed, with the finger of blame (not the Little Dutch Boy’s) pointed at a species of cased-caddis fly which was found clamped onto the freshly bored holes. Smoking gun indeed.

Many people’s idea of a pond is to use concrete. This works out fine, as long as you add a water-proofer. In dry weather the pond gradually drains, with unsustainably large populations of water-louse and bloodworms gathering in the last muddy dregs at its bottom. I speak from experience, having also experimented with mortaring beach pebbles as an alternative. Same problem. A liner underneath the mortared pebbles might have worked. In the end I had to put a liner over the top of the pebbles and now it just looks like a dustbin full of rainwater and duckweed.

Some folk go for the shiny black pond liners. These are a mistake to my mind, since they too look like someone has left a bit of dustbin liner in a hollow on the ground. These ponds can be improved considerably if sand or round pebbles are put on the bottom, but the sides invariably still look like something a 70’s punk-rocker might have warn to a Sex Pistol’s gig (although without the requisite spittle of that era). It is a mistake to be tempted to put soil into the pond as this just enriches it with nutrients, leaving what may be an excellent wildlife haven, but one jam-packed with filamentous algae. Not an attractive addition to the garden this.

However, I think that by hook or by crook I may this year have finally achieved the perfect pond. It was not an easy affair and not without setbacks. I decided to sink a hole into my elevated patio, only to strike a landfill of buried garden waste at a depth of 18 inches. Items such as spade handles, chicken-wire and a window frame, complete with shards of broken glass, lay in wait ready to puncture my pond liner. I quickly backfilled and determined that a shallower pond would be acceptable, perhaps with the sides built up a little to increase the depth. In actual fact a relatively shallow pond is probably best for most wildlife. I added carpet to the underside of the pond liner, to give extra protection from the buried dump beneath. Even in clean earth, a protective carpet is a good idea underneath, because later repairs are near impossible to achieve. I then added a non-turquoise carpet on top of the liner (with the hessian back uppermost) and added water.

I should add that the pond-liner this time round was of a substantially thicker gauge. As years have advanced I have outgrown my Yorkshire parsimony in favour of taking a more sensible longer view. Cheap-skating can be a false economy, especially as far as pond-liners are concerned.
After a week I realised that my pond was quickly losing water and my heart sank. Tracing and fixing leaks is a nightmare scenario, especially when you have gone to great lengths and expense to avoid it. I then recalled a similar situation with a professionally installed pond at an environmental centre where I once worked. When the installer was alerted to the problem he quickly solved it by adjusting the protective geotextile cover placed on top of the liner. The geotextile was wicking water into the surrounding dry soil at a rate of knots. I took a similar view to my own problem , breaking the contact between the carpet and the surrounding soil. Problem solved.

Even the perfect pond has problems on the way to achieving perfection. My next one was the awful smell of decomposing carpet that ensued after a couple of weeks. If you have ever had water damaged carpet, you will know the smell in question. I just couldn’t get near the pond without feeling nauseous. On checking the advice to be found on the Internet I quickly realised where I had gone wrong. Never use a natural fibre carpet as your top-liner, since it quickly starts to biodegrade. Apparently synthetic ones are ok. Rather than remove it completely I decided to cut the carpet just below the water-line. This is a delicate operation to carry out, since sharp blades and pond liners are not the best of bedfellows. I suspect it was the carpet languishing in the oxygen-poor deeper water that was creating the odour, since the smell disappeared almost immediately.

A week later and the water level held good, nasty niffs were non-existent and the bottom of the pond – was totally obscured. Why was my lovely garden pond not a crystal clear lagoon? Instead I had something that my wife’s son described as “looking a bit septic”. For the next 3 weeks or more the bottom of the pond remained as visible as a black hole in the cosmos. Then suddenly the water cleared within a single day. Green is my favourite colour, except when it comes to water. Clear water however, is a beautiful sight to behold.

Whilst my pond was busy being ‘septic’ it also went through a number of other biological progressions. I had decided not to introduce any animals to the pond, other than those that might already be living in amongst the roots of a white water-lily transplanted from a failed pond elsewhere in the garden. First to appear were the mosquito larvae so common in garden water butts. These little chaps did their bit for the pond, since they were one of the creatures responsible for controlling the green unicellular algae that were the cause of my ‘septic’ distress. Within a few weeks water-louse and bloodworm were to be seen. I suspect they came with the white water lily. However, other flying visitors soon sought out the watery oasis in my garden, including greater and lesser waterboatmen, pond skaters and water beetles. A single whirligig beetle stayed for a couple of weeks, but gave up and decided to go in search of love elsewhere.
Soon duckweed was spreading across the pond, which in turn brought in conjoined damselflies flying in tandem. The males holding fast to the female’s neck whilst she carefully cemented eggs to the underside of the duck weed. Two or three species of dragonfly also came buzzing, including a broad-bodied chaser, which I initially mistook for a hornet. This plump lady was far less assiduous in her placing of eggs than was her damselfly counterpart, electing to spray her eggs over the pond vegetation as though from a sawn-off shotgun. Within a couple of months the pond was awash with invertebrate life. However, the most welcome were the water fleas. As their numbers multiplied a critical tipping point was reached. It was they who consumed the algae at such a rate that they caused the water to clear within 24 hours.
My 6 foot by 6 foot pond is now a beautiful haven of wildlife. The white water lily is rooted in the deeper water and provides cover across a good third of the pond for at least a dozen genera of pond invertebrates. A number of vertebrates have also visited including a frog and a yellow wagtail snatching pond skaters off the lily pads. Menacing broad-bodied chaser larvae scuttle across the pond floor like big-cats in a miniature Serengeti.

The latest development is germination of monkey-flower seeds in the damp hessian back of the carpet I left above the water line. The hessian dangles sufficiently in the water to provide a damp substrate for the monkey-flower to gain roothold. This and other such plants will disguise the pond liner on the vertical sides of my pond. Elsewhere, pond plants are colonising the shallower waters essential to any good garden pond.

Only a few visitors have so far been invited to marvel at this beautiful addition to my garden. Doubtless someone will eventually say “Don’t you have any fish?” To which I will reply “The pond is too small. If you have fish in a small garden pond they will eat everything in sight. You can’t have fish and wildlife.”
As my pond matures I just love to gaze into the clear water for long hours and watch all the ‘water babies’ at play and wonder at nature in miniature.

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david horne

I am a Forest School leader, interested in developing a love of the environment amongst children. Forest School and related educational activities draw children outside to enjoy the natural world. This is essential if they are to be the next generation of environmental guardians. I have a degree in Botany/Geology and have been in environmental education since 1979 working for a number of organisations, such as the Field Studies Council, Canterbury Environmental Education Centre, Essex Wildlife Trust, London Wildlife Trust, Wat Tyler Centre, Surrey Wildlife Trust, Bromley Environmental Education Centre and Wilderness Wood. I currently work freelance with schools and other organisations. I would like to write regularly for children and those interested in their education, looking at the world through the eyes of a child, rather than as an expert.

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