The first step in actually building a rock garden is to lay it out, at least in enough detail to show its general outline, indicate pathways, and so on. These points are best marked by fairly strong stakes driven into the ground, otherwise they will likely be obliterated.
Where there are no ledges or stones to begin with, some excavation is required. This is not solely for drainage. If the rock garden is only laid out on the surface of the earth, there will be an interruption at this point, which will severely affect the moisture supply.
The base or foundation
The base or foundation of the rock garden structure should be literally buried in the ground. The foundation should be mostly stone, with any patio statues left for later use. Small fragments, flat stones, soft rock or slate, rock debris of any kind that are not suitable for use above ground can be used advantageously for “filling in”.
Old brick or masonry scraps will answer; Ash (not soft ash) performs admirably. The bases of the largest rocks whose tops appear above ground should be sunk well below ground. Incidentally, the excavation carried out provides usable soil above ground.
Often less on a slope or bank
Under ordinary conditions, where the subterranean drainage is good, 12 or 15 inches will be deep enough for this preliminary excavation; often less on a slope or embankment. If the ground is hard, it should be broken up thoroughly with a pickaxe. Many authors recommend a dig of three or four feet. It’s much easier to recommend than to execute – you’re more likely to want to execute Garden Construction the recommender. Such a depth is only required when drainage is unusually poor.
When the excavation is complete, the ‘skeleton’ of the rock works can be put in place – the larger stones being placed in position and a sufficient number of others placed at key points where construction is to follow. The steps, if any, can also be inserted.
The construction of the rock garden
The construction of the rock garden can be done in different lines depending on the type of construction and local conditions. These can be classified as follows:
The Mound Rock Garden:
Where one must start “on the plain” and with no naturally occurring rocks, the simplest form of construction is the form of a continuous hill or ridge. This can be “turned on” in both directions or only in one direction.
A row of the larger stones can be placed along the edge or edges first. They, of course, should not be laid in a straight line, nor should they touch each other, and the spacing should be uneven. Then fill in a layer of rock and earth on the back and continue building.
The surface stones should be laid flat
The surface stones should be laid flat and pointing downwards, both for stability and to catch and drain into the ground as much rain or condensing moisture as possible, which can be caught by their protruding edges. Constant observation is required to turn the most attractive side or face of each stone outwards.
Almost always, each stone should also be placed with its natural base down. The soil used in construction should have been prepared in advance. Nevertheless, each stone should be absolutely firmly in place. This applies to terrace waterfalls that are integrated into the rock garden .
The sunken or semi-subterranean rock garden:
Often the garden is not built entirely on the surface, but is formed by digging up a significant portion of the area to be used, throwing up the soil removed around the edges, or piling it up along one side. Of course, this arrangement involves more work, but it has several advantages.
In the first place, it allows for a wider range of conditions under which the plants can be grown. If you value the largest possible selection of stone and alpine plants, this is important.
But this excavation should not have the character of a hole in which water can collect.
Which can be stacked around the outside
A depth of four or five feet below natural soil level accommodates planting six to eight feet tall.
Sometimes there is an old cellar hole, natural hollow or other depression that can be used in this way. Even a small excavation, no deeper than two or three feet, opening from one side of the rock garden, normally laid out on the surface, will provide not only a pleasant change in the general plan, but also shade and shelter for different species of plants.