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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.

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Dwarf evergreens and dwarf shrubs will help to produce the illusion of naturalness in the rock garden to a greater degree than any other form of plant materials, if they are used in the right way. There are very few rock gardens, indeed, regardless of their size or character, which cannot be made more attractive by the addition of some of these dwarf plants.

The most serious problem in connection with their use is indicated in the four words above-”in the right way,” for these are plants quite as effective in destroying whatever naturalness there may be as in adding to it. Unless suitable types are selected and so placed that they do not look formal or artificial, it is far better to omit them entirely; and placing them where they will contribute the desired effect is no easy matter; it requires good judgment, taste, and, above all, an eye for composition.

To begin with, we must keep in mind that these plants are to be used not primarily for themselves, but to supplement the rocks in creating an environment for the rock plants. The rocks, dwarf trees, and any patio statuary (http://www.garden-fountains.com/Detail.bok?no=3416) form the setting of the stage, and the placing of both should be studied with the same painstaking care.

It is not necessary to stay within the limit set for the rock plants, but it is most essential to maintain rigidly our sense of proportion. Excepting in the very smallest of rock gardens, we may employ conifers towering to the sky-scraping altitude of two or occasionally three feet.

The beginner may be surprised to learn that there are a number of perfect tree-like little specimens which do not grow taller than this. Even with these giants, the greatest care must be taken not to place the largest of the rock plants in close proximity to them.

Habit of growth is equally important. There are, for instance, many of the dwarf evergreens of such perfect globose form that they look almost as though they had been turned out of a mold. While excellent in formal gardening, these are not in keeping with the rock garden. Such strictly formal things as clipped or shaped dwarf evergreens or box bushes, it hardly need be said, should never be allowed near the rock garden or any defining wall water fountains.

Some of the low-growing, spreading evergreens, as certain of the creeping junipers, while not too tall growing, are still too coarse in habit, eventually making plants which are so large in diameter, if not in height, as to look out of place.

The character of such evergreens or shrubs as may be used in the rock garden is, if anything, more important than the character of the individual rock plants. They show up more conspicuously, and are in evidence throughout the entire year.

Dwarf forms of the tall-growing coniferous evergreens, such as spruces, pines, and firs, are generally somewhat picturesque in character and will suited to rock-garden planting. Where one can visit a nursery personally, it is sometimes possible to find specimens which are “imperfect” from the nurseryman’s point of view, unevenly developed, crooked, or otherwise “deformed” which are admirably suited for rock-garden planting.

These not only make most desirable subjects, but as a rule are to be had at a much lower price-if one does not appear overanxious to get them. There are rock gardens, famous for their Japanesque effect and garden water features (http://www.garden-fountains.com/Detail.bok?no=2912), were planted largely with such undesirable specimens from old nurseries.

The Japanese create character and the appearance of great age by skillful training and pruning; there is no reason why the rock gardener should not experiment in this direction, but if it is a new field to him he must be prepared to make mistakes, and possibly to spoil some plants.

A General Purpose Rock Garden Soil

The gardener knows that there is nothing like coarse, gritty sand for increasing the drainage properties of a soil. He uses it in his cutting bed, in the soil he mixes for potting. So sand will be one of the ingredients.

The roots of rock garden plants, as we have seen, like to cling around the moist surfaces of bits of stone buried in the soil, while the leaves rest upon those pieces which work their way to the surface, thus avoiding direct contact with the dirt.

An important ingredient will be stone chips. Ordinary crushed stone, such as is used for surfacing roads is suitable; this can be readily procured in most sections. If not, bank gravel, preferably not too fine or smooth, and not “washed,” will serve as a substitute.

For our third ingredient, we add humus or decayed vegetable matter, which is found almost invariably in soils in which rock plants grow. This material holds an additional supply of moisture, besides furnishing some plant food. For supplying humus, granulated peat moss is best. It is so slightly acidic that only the extreme lime-loving plants object to it, and it absorbs and holds more moisture than any similar material.

Moreover, it is both pure and absolutely free from weed seeds, an advantage which cannot be overemphasized in rock garden planting. Peat moss is now readily obtainable anywhere; but if you do not happen to have it, finely sifted leaf mold will serve. Commercial humus has more of a tendency than either of the above to get wet or soggy.

Fourthly, and lastly, to give additional body to the plant food, we add good light garden loam. This, however, should be wholly free from clay, which is the last thing, in the way of soils, to be used where rock plants are to go.

All this has required some time in the telling, but if you boil it down it comes to this. To make a satisfactory all around rock garden soil, mix thoroughly together the following:

1 part clean, gritty sand, 1 part stone chips, or clean, gritty gravel, 1 part granulated peat moss, or sifted leaf mold, 1 part clean, light garden loam.

You will have a soil in which 90% of the rock plants you are likely to try at the start will grow satisfactorily.

Special Soils for Special Purposes

Occasionally, however, you will find plants that require something different from the above in the matter of soil; these will grow in the above mixture, but will grow better if their tastes are catered to.

Some insist upon having an extremely acid soil, or a lime soil, in order to survive at all. Such plants as these may either be grouped by themselves, or may be started in pockets filled with a soil supplying their own special dietary requirements.

These special soil mixtures may be made up according to the following prescriptions, the chief changes being an increase in one part or another of the several ingredients. These proportions are approximate; there is no necessity for weighing out the ingredients on a jeweler’s scale.

Acid Soil

1 part sand, 1 part stone chips, 3 parts acid leaf mold (that is, leaf mold gathered from under evergreens, laurels, or the like), Lime or Sweet Soil 1 part sand or 3 parts old plaster, 1 part loan, 1 part peat moss

Dry Soil.

3 parts sand, 2 parts stone chips, 1 part loam, 1 part peat moss

Moist Soil.

1 part sand, 1 part chips, 1 part loam, 3 parts sphagnum moss or granulated peat moss, or both

Fertilizers

For plants other than the true rock plants and alpines-such as garden perennials and annuals, shrubs, evergreens, and most bulbs-and also for such of the rock plants or alpines as take readily to a somewhat stronger diet, very often decayed manure and bone meal may well be added to the general soil mixtures suggested above.

For evergreens, shrubs, or other plants which are to be set around the rock garden, by way of a background or setting, such conditions as are usually provided for them should, of course, be given. Particularly if any specialty garden features have been added, such as those in the Williamsburg Collection, http://technorati.com/videos/youtube.com%2Fwatch%3Fv%3D9HrZ2bNaiGk.

Do not use any of the commercial fertilizers, except bone meal, and even with this great caution should be exercised.

Lime is not a fertilizer, but may occasionally be needed for the rock garden. If old lime rubbish, which is better for this purpose, is not to be had, ground limestone or gypsum may be used, to modify a soil otherwise too acidic.

Aluminum sulphate, now offered by most seed houses, works in the opposite direction. This may be utilized either to neutralize a lime soil, or, by applying it in larger quantities, to make the soil acid-reacting. Acidic leaf mold, which is to be found in most sections if trouble is taken to hunt for it.

Leaf mold gathered under oak trees is sufficiently acidic for most purposes, if decayed laurel leaves, conifer needles, or rhododendron leaves are not to be had.

Product Description
Garden expert Loewer offers gardeners a way to turn their dreams into full-flowering reality even in limited spaces. Guidelines are given for choosing the best plants for a host of gardens, including dwarf conifer gardens, alpine gardens for rock plants, moss gardens for shade, and trough, tub, and pot gardens. 40 illustrations.

The New Small Garden: Plans and Plants That Make Every Inch Count

While it may be immaterial where our plants for the rock garden come from, in so far as the effects which we create with them are concerned, their origin does make a difference in regard to the culture to be given them. For this reason, if for no other, it is desirable to know something of the differences in the several classes of plants available for rock garden use.
But in addition to this utilitarian advantage, there is another of quite equal importance. Even though one may know little, and possibly care less, concerning botany, any plant takes on greater interest when we know something of its associations and its history. In fact, it is impossible to dissociate these from the intrinsic qualities of the plant. The edelweiss of the Alps, for instance, “without which no rock garden is complete,” in the opinion of some, is but a tiny flower surrounded by a bract of white woolly leaves, which would be passed by as a modest weed if it grew by the garden path.
But when one has read of adventurous spirits risking limb and life to find it blooming among the snow and ice of alpine heights, it naturally assumes an interest more than commensurate with whatever beauty it may possess as a flower. The more you know concerning your plants, whether in your rock garden or planted amongst your patio statuary, http://www.garden-fountains.com/Detail.bok?no=3254, the better you can provide for them and the greater the joy which they may give you.
Alpine Plants:
An “alp” is a high mountain anywhere, not necessarily, as many people take for granted, one of the range in northern Italy and Switzerland; it comes originally from the Gaelic word for mountain pasture.
True alpine plants are mountain plants from any part of the world, native to those altitudes above the timberline, and extending as far upward as any vegetation can survive. They grow where the natural drainage is exceptionally good, but where their roots are constantly supplied with moisture, mostly from melting snow and ice, and consequently nearly ice cold. The season for growth and flowering is brief, often little over one hundred days.
Logically, the nearer one may approximate these conditions in making a rock garden, the better are the chances of success with this particular type of rock plant. Those who live in northern sections, at comparatively high altitudes, especially where the growing seasons are short and snow remains on the ground for months at a time, have an advantage over the rest of us when it comes to alpines.
Subalpine Plants:
Occasionally, in the catalogs or in rock garden literature, we will find the term “subalpine.” This applies to plants of alpine character which grow somewhat farther down the mountain slopes, below the timber line.
Such are more likely to tolerate some degree of shade, and, while absolutely hardy, not so likely to enjoy standing with their feet in cold water. These plants are ideal for gardens with outdoor water features that provide shade.
Mountain Plants:
Still others there are from the lower mountain regions, foothills, and rocky slopes, which possess many of the characteristics of the true alpine plants, but which naturally are still more amenable to such a home as may be provided for them almost anywhere; insisting, nevertheless, upon exceptionally good drainage, and soil which suits their wild nature, and frequently, in ordinary rich garden soil, either going to one extreme and perishing outright, like the trailing arbutus, or to the other and getting so fat, flabby, and bourgeois that their beauty vanishes, as is the case with the wild columbine.
Moraine Plants:
Plants which, in your catalogs, you find specifically recommended for moraine planting, cannot be expected to give equal satisfaction elsewhere. The combination of an almost perfectly dry surface soil and a more than usually abundant supply of moisture at the roots, is not generally to be found unless there is special provision for it. Planting moraine plants near outdoor water falls (http://www.garden-fountains.com/Detail.bok?no=1067) is not recommended, due to the need for a dry top soil.
Moraine plants constitute, therefore, a class which the beginner will do well to keep away from, unless he has the means for providing the special conditions they require; even then, it will be better to wait until experience has been gained with plants more easily managed.
Bog Plants:
Most of the bog plants, on the other hand, are very readily handled. They grow in wet places, but not actually in the water, like the aquatics. Note should be made of the fact that there are many alpines and rock plants recommended “for moist situations,” or “moist soil,” which are not bog plants; that is, they will not thrive where there is water standing in the soil, as the genuine bog plants, such as the marsh marigold, or pitcher plant, do.
Many of the bog plants which, in their native locations, are covered with water for several months of the year, will get along nicely in much less moist (but not dry) situations. The native iris and the cardinal flower are examples of these.
The bog garden, however, is not logically a part of the rock garden. Many plants often included in alpine and rock plant lists, which really belong to the bog garden, merely serve to confuse the beginner. If one is starting out to make a rock garden, there is no necessity for wandering frequently or far into the swamps in search of material for it.