To make a marginal bog garden you can either build a double wall to the, i.e., a wall to the deeper portion that will come an inch or so below the water surface, leaving an outer concreted trench that has a wall a few inches higher, the trench being filled with prepared loam, or you can make the complete pool first all the same depth, and then build with bricks an inner wall, coming nearly to the water surface. The space between this inner wall and the outside can then be filled with soil for the reception of bog plants. If a fountain is to be included in the feature, it will be set in first, and the concrete laid round the pipes. Similarly, if a waste pipe for emptying the pool is desired, this will be set in position first. An outlet for surplus water just below the ridge of the concrete, or just below the coping stones if a formal finish is given, should be connected to the sump or ditch. An inlet pipe, for large pools, will of course be set just a little lower, and if company’s water is used a tap will be required. (A meter will be installed by the company.)
With regard to the style and finish of the pool, a simple method for an amateur to adopt is to lay slabs of paving round, slightly overhanging the sides, and flush with the lawn in which the pool is set. Another method is to use large and small rocks, informally, with waterside plants grouped among them. This is possibly the best method of all in a little garden, for with a boggy section, a deep water section, and a margin of decorative plants, theadds enormously to the number and variety of plants that a little garden can contain.
If, remember, the primary object of the water is to enable water gardening to be practised, fountains should be looked at with suspicion. Water lilies and many other aquatics dislike constant disturbance of the water.
Because of this, fountains are more generally associated with formal pools than with informal ones. There are, however, a great variety of fountains, from the simple perpendicular jet to huge cascades, and a type that must not be overlooked by the small garden owner, the small figures, such as frogs, that send a spout of water, as if from a hose, across the pond. This latter type can be used in association with the informal water garden. It will not be in constant use, but will be turned on occasionally, and water played over the surface in this fashion is really the best way to keep up the water level during the drying days of midsummer. These figures are not costly, and can easily be connected to the water supply.
A pond with a fountain is a never ending source of delight. To many the matter of water supply has been the stumbling block. But a spring or a supply from the mains is not essential and, in fact, mains water can be harmful to the plants that grow in or near water. It is far better to use the water in the pond which is at atmospheric temperature. If it is circulated through a fountain or waterfall in the rock garden it will remain aerated and sweet, and fish will thrive in it.
The main characteristics of the centrifugal pump are as follows :—
- The higher the head the smaller the quantity of water and the less power consumed.
- By decreasing the head the quantity of water delivered per hour will be greater, but proportionately more power will be required.
- The height or volume of this jet can be decreased by an adjustable jet without harming the pump.
- A foot valve is necessary if the pump is installed above water level, otherwise the water will run out of it and the pump will have to be recharged every time it is put into use.