How to build a Rock Garden

Rock Garden

Rock gardens are usually planted with alpine plants. The rocks create a natural and decorative setting against which the alpines look at home; indeed, the rocky site provides the perfect, free-draining habitat with a cool root-run which alpines require if they are to thrive. Rockeries can be any size; they can vary from small arrangements built on patios where paving stones have been removed, to large features that take up most of the garden.

The site can be of any aspect but an open one with plenty of light and air is preferable. Although alpines will tolerate high winds they do not like draughts, so avoid constructing a rockery where wind is likely to be funnelled between buildings or trees. Rock gardens look best on sloping sites, but they can also be built on flat ground to make horizontal features.

The soil must be carefully considered. A free-draining loam is best if it can be obtained, otherwise a mixture of one part good garden soil, one part coir, peat or leaf mould and one part grit or gravel, as measured by volume, can be used; the grit or gravel is important as it will aid drainage. The soil used must be completely free of weeds, otherwise the rock garden may have to be dismantled so that the gardener can thoroughly weed the site.

Rockeries are attractive features in their own right and the choice of rock is important. If possible, use a local stone which will not only be cheaper but will also look more natural. Do not use lumps of concrete as these rarely look right, and in particular avoid using a soft stone that is more than likely to shatter and flake during the first frosts.

The rocks should be arranged so that they resemble the strata of a rocky outcrop rather than being dotted around on the surface of the soil. Each rock should be partially buried in the ground. This will create a more natural look and provide the plants with a cool root-run, as well as making the feature more stable so that people can walk across it to admire the plants.

For a more varied feature, certain areas of the rock garden can be given different soils so that a wider range of plants can be grown. Areas shaded from the sun during the hotter part of the day should have more organic material, such as peat or leaf mould, incorporated into the soil to make it more moisture-retentive; primulas love damp soil and these and other plants suited to moist conditions can be grown. Crevice plants can be worked into the vertical cracks between the rocks which will provide the sharp drainage that they require.

There is a vast range of plants that can be grown in rockeries but the majority flower in the spring. Try and include some summer- and autumn-flowering plants as well to give as much seasonal interest as possible. Rock garden plants need not be restricted to those from high alpine regions; many dwarf lowland plants are excellent choices. Small bulbs in particular can look very attractive in rocky settings.