Often the stones of which the rock garden is to be constructed may be obtained locally; sometimes on the place itself. Under these conditions, we must usually take what is available, and make the best of it. But not all stones are equally appropriate for rock garden building.


”Sympathetic” Stones


If rock plants ask for bread and you give them a stone, they will be very well satisfied-if it is the right kind of stone. Some rocks, due to their character and texture, are termed “sympathetic” to plant life. This depends, primarily, upon their porosity-the capacity for absorbing and storing moisture, and thus encouraging the creeping, thirsty roots to hug the rock and follow its surface deep down into the soil.


If you have roamed through fields and woods, or have stones about your own place, you have undoubtedly observed the difference among them in this respect. Some stones have a smooth, close-grained surface as impenetrable as marble; others are so porous that they will almost drink water like blotting paper.


Neither extremely hard nor extremely soft stones are best for rock garden making; the former are not “sympathetic” to plant growth, and the latter are not practical because they so quickly disintegrate

and crumble, often going to pieces in a single season when exposed to rains and frost action, although they may seem fairly substantial when put in place.


Types of Stone to Use


Hard, close-grained stones like granite are often used because they are easiest to get. If the pieces are irregular and with rough surfaces, as mined from a quarry, they will serve the appropriate purpose. Field stones or boulders, frequently found in places where there are glacial deposits, ground to smoothly rounded surfaces, are the least desirable.


Limestone or sandstone which shows a distinct grain or stratification, and obtainable in irregular blocks of varying sizes and shapes, is the most desirable. Field rocks, if not too small, are also brilliant, particularly if they have weather-beaten, or moss or lichen-covered surfaces.


Even in a small rock garden, it is well to have at least a few “old he-ones”-rocks which take a great deal of pushing and possibly some strong language to get into place; but which, once you get them where you want them, will give character to the entire planting.


They possess beauty and individuality no less than the plants with which they are to be associated. Japanese gardening is almost literally rock landscaping. In many of the wonderful compositions in Japanese gardening it is the plants, rather than the rocks, which are subordinated.


Tufa Stone is a volcanic rock, extremely ornamental both in form and texture, extraordinarily porous, light, easy to arrange, and in many ways desirable. Its cost, determined largely by freight charges, is not prohibitive for use in a small rock garden, especially where a picturesque or Japanesque effect is desired. It does not fit so well into a natural rock garden and looks best with a garden fountain, http://www.garden-fountains.com/Detail.bok?no=2918. This material is handled by many concerns which specialize in rock plants.


Other Materials


Rough slate, which is suitable for many garden uses, is best omitted from the rock garden, unless possibly for the making of paths, steps, stone seats, or similar features that employ patio statuary, like the Williamsburg Collection, found at http://technorati.com/videos/youtube.com%2Fwatch%3Fv%3D9HrZ2bNaiGk, and where there is no reason for not using a type of stone different from that employed for building the garden itself.


Old weathered logs of wood are sometimes employed in the construction of steps, or to hold an embankment in place. One serious objection to wood is that it decays quickly; but in appearance, if chosen with good taste, is satisfactory.