Making a Pond

Start your planning by thinking about a pond. It might not be practical in your garden, but they are marvelous features if you can include them and they are even better if you can incorporate a stream and a bog garden. If you can include this feature the ideal would be for slow moving water and a small cascade or waterfall. Slow moving water in a garden is a better habitat than a rivulet that rushes along so fast that all the animals have to hang on tightly to avoid being swept away, though there are some that thrive in this environment. The cascade is recommended because the humidity around it is great for some ferns and other plants that appreciate these conditions. The pond itself should not be of even depth and a shallow shelf around the edge and a deep bit in the middle, is fine, but it is an ideal arrangement would be for the stream to end up running through the bog garden before entering the pond which slopes from a depth of a few cm (in) at this end to 60 cm (2 ft) at the other, with maybe a marginal shelf at the deep end.

Nowadays the choice of materials for pond making is larger than ever before, but if you can afford butyl rubber, use that, though it is more expensive than some of the other options. The great advantage of polythene is that it is cheap but even the thickest grades will not last long before a leak appears, and it is almost impossible to seal even if you can find the hole. The laying of concrete is a difficult business and, although it can be undertaken by a novice, it is better for a professional to do the job. It is not a cheap undertaking for, in addition to the materials and labor, wooden shuttering has to be built to hold the concrete in place while it is drying.

If you have opted for a pond liner, this should extend beyond the pond to cover the bottom of the bog garden or the water will simply soak away. When you have dug the hole, you should find and remove every sharp stone on the bottom, and if you come across any roots do make sure you get rid of them rather than saw them off, because if they start to grow they will make a hole in your pond. Plants are amazingly strong things that on occasion even force their way through tarmac and pavements. When the inside of the hole has been cleared it is a good idea to coat it with a layer of damp sand that acts as a good smooth surface on which to bed your liner. If you are using butyl rubber the next thing to do is to line the hole with the fibrous matting that is supplied as a base and then lays the rubber on top. There should be a fair bit of excess rubber above the edge of the hole as when water is added the rubber will settle deeper into the depression. I have assumed that you will not want a formal pond. If you do, you have to ensure when you are digging the hole, that the top edge is level, using a spirit level to check; otherwise you will inevitably find that on one side the water is flush with the top of the hole while on the other you have several cm (in) of bank exposed above the surface. With an informal pond a bank at one side is not a bad thing at all.

When you have reached this stage put a few bricks or lumps of rock on the edges of the rubber to hold it down, drop the end of the hose into the hole, and turn on the water. It takes far longer to fill even a small pond than most people realize, but eventually, perhaps even a day or two later, the water will reach the brim. Cutoff the edges of the butyl rubber to leave about 30 cm (1 ft) lying on the ground all the way around, and start to landscape the new area by placing suitable rocks around the edge to overlap the water a little. There should be spaces here and there so that little animals can get between them to the water's edge and do provide lots of holes and crevices. If you are fortunate enough to have a heap of builder's rubble and broken bricks, put them into a pile and cover them with soil; but leave a few lengths of drain pipe protruding as entrances which can be concealed with plants or by placing a rock over them. This pile of rubble is an excellent place for amphibians, reptiles and even small mammals to shelter beneath the frost during the winter. When everything is to your satisfaction shovel soil over everything to make it look natural, adding any topsoil, peat or whatever as necessary.

The pond itself is now ready for attention, and you can start by putting something in the bottom. Pea shingle is a good idea and you can buy this from a builder's merchant, but rinse it thoroughly to remove any pollutants such as petrol residues. At this stage I like to add a couple of buckets of sludge from the bottom of a natural pond to the bottom of a new one. It may look like a foul black slime but it is a rich biological soup which is packed solid with living things - which is why you should not tip it into a new pond until a couple of days after you have filled it with water since tap water contains chemicals which kill small life forms. The sludge from the natural pond will act as a starter culture for the new pond. If the water looks absolutely awful when you first tip it in, do not worry, the sludge will settle and the water will clear in a few days, and soon you will discover that it is full of Daphnia, protozoan’s, diatoms and other animals. If the pond is large enough and you know someone who keeps native species of fish from whom you can get a few, introduce these into the pond. It is not a good idea to put in any Goldfish; these grow to such a size and will soon eat every living thing in the pond, unless the volume of water is very large.