In districts where quantities of stone are easily obtained, division fences often take the form of stone walls. The whole wall may be of stone, or there may be a low stone wall above which trellis, or other screens, are erected. Walls of this type should invariably be built within some of the crevices instead of cement, so that the wall itself can become beautiful with age. If they are well constructed, and laid on a foundation of ballast and cement, such walls are quite as satisfactory as walls built of cement, and are always more picturesque.
All high brick walls erected as boundaries can be clothed with. They are, of course, ideal for growing fruit trees of the cordon, espalier, or fan-trained type.
A retaining wall is not built quite vertically, but slopes back slightly towards the top, and each stone slopes a little downwards into the bank.
The type of stone used for walling is usually either sandstone, which is a hard brown stone, supplied in pieces three to four inches thick, or York stone, which is greyish brown in colour and is used for more formal walls, and generally bound together with cement. A ton of stone builds approximately four square yards of wall.
Yorkshire stone, when cement only is used with it, makes a feature that looks stony-hearted, and the gardener who loves plants and wants to include them wherever possible, will be wise to give preference to the sandstone, built with soil in the cracks.
The method of wall-building is simple. It is desirable to slope the wall as it is built from the base upwards, and a stake driven in vertically at the base will help the builder to keep the slope even. A quantity of soil is prepared by sifting sand, loam, and leaf-mould together, and this is rammed between the stones, leaving no air spaces behind them. Every few feet, a long stone is allowed to penetrate into the soil behind, to bind the whole firmly.
Each stone must rest firmly on the one below, without wobbling. If cement is used in the place of soil, “tear holes” are left at intervals of about six feet, to allow water to drain away, otherwise the stones may be forced out of position.
It is sometimes best to use cement in some places and soil in others, for greater safety, and good use can often be made of a little cement to construct a kind of rude pocket, which will hold an extra large supply of good soil for a special plant. This is a touch which makes a new wall look quite an old-established feature.
If possible, the plants are set during building, for this is easier, and less likely to end in damage to either the plant or the wall. If they cannot be easily obtained at the time the wall is made, it may be best to use seeds. A ball of soil, with a few seeds intermixed, moistened, and pressed into the cracks of a completed wall, rapidly produces plants that look as if they came there by the hand of Nature.