Rock Gardens and Choosing the Right Stone
ONE reason why ais such a popular feature amongst amateur gardeners is that it can be any size from a square yard to a square mile. It is hardly too much to say that there is as much interest to be found in the cultivation of a small rock garden as in a larger one. In many cases there may be found more interest, owing to the fact that the type of rock garden that would be made in a small space would probably be one that contains rare Alpines. The larger rock garden would more probably be designed on spectacular lines as a piece of natural landscape with bolder planting of subjects that are more common in gardens.
Obviously the first thing to do in considering a rock garden is to decide what type it shall be, and this involves questions of site; locality, and cost, as well as personal preferences. If the garden is being made on a sloping hillside, the rocks could be introduced either in the form of a sloping rock garden, or in the form of a rockery retaining wall between sections that are levelled to form terraces. In either case, Alpine plants of many kinds can be grown with picturesque effect.
If a rock garden is to be made on a site that is perfectly level, considerable excavation and building-up have to be done. This, of course, adds to the initial cost, but it makes comparatively little difference to the subsequent cost of upkeep.
Choice of Stone
One of the problems which must immediately be decided is what kind of stone shall be used. There is a very simple rule which can be followed by amateurs in this connection; that is, to use the cheapest available good stone. It will be found that in most cases this works out satisfactorily from an artistic point of view. In the first place, the cheapest stone is probably stone which is quarried locally, and this stone is generally best suited to the surroundings of the garden. In some cases, it will be stone similar to that used for architectural features in the house (for instance where houses are built of stone as in midland rural districts). It is also the stone which is likely to be somewhat similar in nature to theof the locality, and plants that will nourish in the ordinary soil of the gardens will find an equally happy home amongst the local rocks.
In the case of aof a developing Housing Estate near a large town this matter of stone assumes a somewhat different aspect. In all probability the house is built of artificial brick, and there is no possibility of making the rock garden associate closely with the surroundings. It is therefore, aesthetically, immaterial what type of stone is used.
Water-worn limestone is regarded as being the best and most artistic for conceived on a large scale, especially for rock and water gardens. Smaller pieces of weathered limestone are suitable for small , and make the finest of all homes for a large section of Alpine plants.
Sandstone of various types is quarried in many districts, and is not inferior to limestone in many respects. It is of a porous nature, and consequently holds sufficient moisture for rock plants, and it very quickly weathers to a mellow hue. Where sandstone can be obtained from local quarries it should certainly be used in preference to paying larger sums for limestone.
Another stone frequently used for rockery construction is tufa, a volcanic rock. This again is excellent for certain plants and not unsuitable for any type of rockery construction. Granite is a stone which is generally regarded as inferior by gardeners. It makes a lovely rugged and imposing rock garden, when it can be used in very large pieces.
The amateur who builds his own rockery is however advised to ignore granite as a possible rock, as the size of stones necessary to make a really grand imposing garden would be impossible to move without machinery. All this however, concerns the amateur gardener who has at his disposal sufficient funds to make a choice possible.