Making a Pond in your Garden
Making an artificial pond is an exciting prospect (at least, it is once you’ve dug the hole). This is in any case popular and common practice among gardeners, and many of the better gardening books give excellent advice on what to do. A formal garden pool—even a fairly sophisticated water garden—will provide good conditions for birds, but in many ways a purpose-built pool is better. The only constraints are how much you want to spend and how much space you have available.
Broadly speaking, the aim is to produce a pond with as lightly irregular outline, shallow at the edges (or at least at one end) and not more than 1 m (3 1/4 ft) deep in anyplace. It should provide `walk-in’ access to birds and easily accessible drinking and bathing places. Through admixture of native and more exotic plants, it can be both visually attractive and a good source of food for birds. Pool can be designed in conjunction with another garden pumped up and named in the pond by gravity; producing oxygenation which is essential for successful and productive pond. the alternative is to stock the pool with plenty of oxygenating plants, horn-wort, for example.
A heavy clay soil provides a ready-made pond-liner which will cost you nothing other than a lot of sweat and toil. But soils with good drainage require entirely artificial techniques for which there are three alternatives. It is possible nowadays to purchase quite large, molded glass fiber ponds which are excellent for the small garden. Their major disadvantage is that the size and shape is predetermined by the manufacturers. Preparing a concrete lining, and coating it with plastic paint, gives you much greater flexibility, but is laborious and, once completed, very difficult to alter in any significant way. A better alternative is to line your excavation with heavy-duty polythene sheeting, which is no more expensive than the other methods and is much more flexible in design terms.
At all stages of construction, extreme care must be taken not to damage or puncture the sheeting. It is important to provide a reasonably smooth base on which to lay the sheeting and then to lay it generously, to allow for its movement and settling when soil is placed upon it, and again when you add the weight of the water. Allow aide overlap at the edges and do not trim off the surplus until the whole pond is completed and filled. Again, be very careful not to damage the sheeting if any large stones, plant containers etc are to rest on it.
Rainwater would eventually fill your pool, but it is better and faster to do it from the tap, using a hosepipe. Add a few buckets of water from a local pond to help, introduce the first micro-organisms to the new environment. Allow the water to settle for about two weeks (topping up the level if necessary) before any planting is undertaken. The layer of soil you have placed on the pond-liner will provide most of what you need for planting, but plants in containers can also be placed as required; use some of the soil from the excavation to build up a low surround to incorporate the overlap of the sheeting and to provide a good moisture-retaining base for waterside plants.