Rocks are one of the basic elements of a garden railway. They form the bones of the landscape. I have known people who live in rockless areas to bring rocks in from a hundred miles away. Rocks give texture, depth, and shape to a scene. They can be used to define areas, mark important points along the line, suggest formality, and create microclimates for specific plants. Not only should the stones themselves be considered, but when placing plants, their shadows must be taken into account as well.
The shapes of the rocks must be harmonious with each other and with their surroundings. Look at rock formations in your area or in areas that are similar to the one you are trying to create in miniature.
Rocks, whether they are raw granite or rounded river rocks, should all lie pretty much the same way. This gives them visual continuity and makes them look like they grew there. They should be buried in the ground and not sit upon it. As much as one-third to two-thirds of the rock should be out of sight.
The size and placement of the rocks is important. Dont choose rocks that are all the same size. The inevitable result of this will be a polka-dot effect on the landscape. Use several different sizes of stone in groupings around the line. Groups of five or seven different sized rocks are usually successful. Always use odd numbers in groupings. The eye tends to divide even groups in half.
Individual large rocks can also be used if done in a restrained and tasteful way. Any single large rock will call attention to itself, so it must be placed very carefully. It can be placed below a bridge, for instance, or it could be used as a visual divider between one garden scene and another. But take great care when using these monoliths. They can just as easily spoil the effect as enhance it.
Stones that are artificially placed can add to the scene. A pair of similarly sized stones can be formally placed on either side of the track to mark the entrance to a station, canyon, or other point of interest. Since these will have obviously been artificially placed to create an effect, a natural appearance isnt as important. The stones can stand farther out of the ground, like monuments, creating interest and drama.
Country gardens and paths are sometimes lined with small stones. Whether or not you think this is attractive in full size, it can be used to good effect in miniature. Statues can rest on a stone in a park or open space and a tiny garden-within-a-garden can be marked with rocks. But never, ever paint them white!
The color of the rocks is another important consideration. Any stone can be said to have a natural color, since it is a product of nature. However, if you choose rock with a strong or garish color, it will not fit in well with your created environment. Strong colors in nature are considered natural wonders. In the garden-railway environment, they are just considered bad taste. The rocks must be neutral-colored if they are to be effective in the railway garden. Earth tones are good. They shouldnt be too bright in value. White or pale stones can sometimes be used to good effect, but only with great skill. They will tend to dominate the area, particularly on sunny days, so use them sparingly. Bright pink granites should not be used under any circumstances. Ive seen pink granite used as ballast on full-size railways, and you can see it a mile away. Our goal is not necessarily to replicate what actually occurs in nature, but to create a kind of idealized natural environment, where all jarring elements have been removed.
When choosing and placing the rocks, consider their proximity to the track, the scale of the trains and structures, and how all of these elements will relate to one another when the setting is finished. A rock can easily dwarf a train. This may be quite acceptable, but this effect should be the result of careful planning and purpose, and not an accident, whether happy or unhappy. Rocks can help to define the landscape in which the track appears, or upon which sit the buildings of the town. They should, in most cases, form part of the background and be one of those many things that are almost invisible to the casual observer, but that tell the subconscious mind that all is as it should be.
The stones relationship to the garden and the plantings therein should also be carefully planned. What part will the rocks play in the garden setting? How big are the plants in relation to the rocks, and vice-versa? Will the plants, when they are full grown, obscure the rocks, negating your work, or will they nestle in between them, complimenting the rocks and creating a natural-looking landscaping.
When planning the railway rock garden, the railway, rocks, and plantings must all be considered simultaneously. You must know where you are going before you can decide how to get there. It is sometimes useful to make rough sketches to help finalize plans. These need be nothing more than shapes and masses to help you visualize the finished scene, and may be meaningless to anyone else who might see them.
There are several things to be avoided when placing rocks. One is using sharp, pointed rocks and standing them on end. This is referred to as almond pudding by rock gardeners. Another pitfall to look out for is the use of same-sized rocks, evenly spaced throughout the area (dogs graveyard). And taking a random lot of stones of all sizes, then dumping them hither and yon (devils lapful) is perhaps the worst of all. For a pleasing effect, stones of similar character and differing sizes must be placed with great care and concentration. There are many fine rock-gardening books available. Read some.