There are many different methods of constructing a pond. The easiest to create is a natural pond. This is similar to but not the same as an informal pond. A natural pond can only be created if the ground water level in your garden is very high, e.g. you live in a low-lying region with peat soil. In that case, all you will need to do is dig a hole in the shape you prefer and wait for it to fill up naturally with ground water. You will not need a waterproof liner to separate it from the rest of the garden. One of the great advantages of a natural pond is that it has a natural through-flow of ground water. In all other types of pond you will need to make sure that the water cannot seep away, i.e. the base and walls of the pond will need to be waterproofed. In the past – and even today sometimes – this was achieved by applying a thick layer of compressed clay. If done properly, this works well but it is a huge job and not one a specialist would recommend. Nor is it by any means cheap. Another alternative – not for peat ground however - is the use of a concrete pond. Here again the construction requires specialist craftsmanship. Unless a concrete pond is expertly constructed there is a great likelihood that it will eventually crack, subside or leak. Not to be recommended therefore. This leaves the most obvious methods, i.e. the installation of a preformed pool or the use of a flexible liner.

Installing a flexible liner The installation can be summarised as follows: Dig out the pond in the shape you prefer. Remember you will need terraces for plants and make sure the walls are no steeper than 35°as otherwise the soil could subside. If you want to keep fish in it, the pond needs to be at least 60 to 70 cm deep. If you want a marshy area beside the pond, this should also be dug to a depth of about 50 cm. Ensure that the edges of the pond are the same height all round. Use a straight plank or a spirit level to check this. A lopsided bank is not a pretty sight.

Using the removed soil It would be a pity to get rid of the soil you have dug out of the hole for the pond. You can use it to create different soil levels in your garden or to produce a hillock behind the pond. Always keep topsoil and sterile subsoil separate. You can use the fertile topsoil when the time comes to plant. Filling the pond If possible use clean tap water, as this is the best quality water we have. Installing a preformed pond Lay the mould on the spot where it is to be installed. Draw round the outline of the mould at least 15 cm larger than the mould itself. Remove the mould and dig out the hole, keeping as closely as possible to the shape of the outline. The hole should be no more than 15 cm deeper than the intended depth of the finished pond as the base on which it is to rest has to be very stable. Put a layer of sand in the bottom of the hole to fill up the extra depth (max. 15 cm) you have dug out. Spread this out evenly making it as level as possible. Put the pond in place and check that it is horizontal all over. Correct until this has been achieved. The edge of the pond should project slightly above the level of the surrounding soil. This is essential to prevent water (and contaminants) from running off the garden into the pond. This is the most difficult bit: the mould must be filled slowly with water, while at the same time the sides must be backfilled with soil and watered. Try to make sure that the soaking wet soil layer and the water in the pond rise at the same rate. Take your time and do this bit by bit. If the surrounding water rises too quickly the mould can start to float and the entire digging operation will have to be repeated. If, on the other hand, you do not allow enough water to flow into the mould, it can start to deform, with exactly the same result. Try to stay synchronised! Fill up the top 15 cm with good topsoil, as you will want plants to thrive there. Keep checking that the pond is absolutely level, correcting wherever necessary as you go along. The edges of the mould now still have to be camouflaged. Garden centres stock very useful grow-bags for use on steep pond banks, which soon become well vegetated. The effect is absolutely natural. In view of the fact that toxic substances may be released by the material from which the pool mould is made, the water should be left to stand for a few days before it is pumped out and the pond filled with fresh water. Wait until the water in the pond has had a chance to warm up before you start to plant. This will take about a week.

Planting the pond It is important to start by planting groups of oxygenators. You will need about 4 to 5 groups for each square metre of surface area. They can simply be thrown into the water just like surface floaters and there is no need to plant them. Next, plant the water lilies in their baskets and install them at the appropriate depth. Do the same with the marginal plants and with the bog plants that are likely to become invasive. These plants should be arranged at their various preferred depths. The remaining bog plants can simply be planted in the marshy area. A combination of plants and rocks still makes the best looking ponds, but the price of large numbers of rocks can be quite high.