Our largest pond, the Wildlife Pond’, is artificial. It was originally dug in what was then an open field in 1989 and lined with butyl rubber. This lasted well but by 2014 the pond had been invaded by New Zealand Pygmyweed, an invasive alien plant, and the decision was taken to dig this out completely and re-line the pond. The new liner was made from woven PVC.
The pond is fed by rainwater – we prefer not to use tap water to top it up, and the water level may fall significantly in dry periods. It has been planted with native wild flowers and is home to a wide variety of creatures: several species of dragonfly are regular and many birds come here to bathe and drink. A problem arose in 2016 when we found hundreds of tiny holes in the liner, and after some detective work we discovered that these had been made by the caterpillars of the Small Chinamark moth, which live underwater and feed on duckweed. We have patched many of the holes, but do not appear to have really solved this unusual problem and the water level falls quickly at times, exposing the liner, which is a little unsightly. We are now considering our options, but are in no great hurry because the pond is fiull of life.
Wildlife Pond Essentials
Garden ponds do not have to be large to attract a variety of wildlife, but it helps to follow a few simple guidelines:
1. A pond is best sited in a sunny place, ideally away from trees to prevent it filling up with dead leaves.
2. If you can fill a pond with rainwater, so much the better, but tap water can be used if necessary.
3. The combination of water, sunlight and nutrients (from tap water, soil and even the air) means that ponds will fill up with vegetation. To avoid the pond being dominated by ‘blanketweed’ (filamentous algae) introduce plenty of submerged ‘oxygenators’, such as Hornwort, to encourage tiny creatures that eat algae, as well as plants with floating leaves that help shade the water.
4. Don’t be shy about clearing vegetation from the pond. Best done in the autumn, weed should be left on the side for a few days to allow creatures to return to the water.
4. At least one side should be gently sloping so that creatures can easily get in and out.
5. Plant at least one side with ‘marginals, and preferably have dense vegetation nearby, such as a bog garden, grassy area, shrubbery or even flower beds, to help creatures come and go without being exposed to predators.
6. No fish! If you have fish, you are very unlikely to have frogs, toads or newts breeding in your pond.