ACS Distance Education UK
Rocks can really enhance the natural feel of a garden and provide a great deal of character. They can be used to create a wide variety of attractive effects. In most cases the best results are obtained when the rocks are positioned so that they simulate naturally occurring rocky features such as alpine outcrops, cliff rock falls, or rocky creek beds. In Europe and America, rockeries which feature low growing alpine plants, have been popular for many years.
There are a few basics points to remember when building a rockery:
Rocks can also be used in a broader way including:
SOME ROCKERY IDEAS TO TRY
1. A dry creek bed can be simply constructed by placing a layer of large pebbles and rocks in the lowest part of the garden or into an area of natural drainage such as a small gully or depression. Choose rocks and pebbles that have a well rounded water-worn appearance. Growing native plants, which would naturally be found in this type of environment, will help it to look more natural.
2. Rocks can be used in a more stylised and formal manner in Japanese style gardens. Unlike European style rockeries, each rock becomes a prominent feature, so selection and placement is especially important. A fairly bland surrounding, such as a uniform gravel or sand surface, or minimal plantings enhances the rocks prominence.
3. Dry stone rock walls can be used both as a free standing barrier or as a retaining wall. Dry stone walls are built by stacking rocks or blocks one on top of another without using concrete or any other 'joining' material to stick them together. Each rock needs to be stacked in a way that they interlock as much as possible so that a good deal of stability is achieved. The base of this type of wall should be twice as wide as the main section of the wall. This spreads the weight and provides stability to the upper parts of the wall, and helps prevent the wall from sinking into soft ground. When building dry stone walls you should try to avoid creating horizontal or vertical lines between the stones, and place the larger stones towards the bottom of the wall.
4. 'Wet or fixed' stone falls will give greater stability than dry stone walls, but will generally not give as natural an appearance as dry stone walls. The stones or blocks in this wall are cemented together. A strip foundation should be laid first, with ideally steel reinforcing set in concrete. The stones/blocks are then laid on top. To further strengthen retaining walls, sections of wall can be run back, at right angles to the main wall, into the embankment or soil behind the wall at occasional intervals along the length of the wall. These walls can be effectively cemented with a mortar mix of 3 parts fine sand to 1 part cement.
5. Rock outcrops consisting of two or three, or perhaps even more, large rocks can be buried into a sloped area. Soil can be mounded up behind them leaving only the down slope face exposed, creating perhaps a level area above the rocks where garden furniture can be placed, or the tops of the rocks may also be left exposed to create a contrast to an otherwise smooth slope. In more level areas large rocks can be simply placed on the soil surface and soil mounded up around the rocks to give the appearance of a natural outcrop. This is an easy way to create a raised area that will add interest to an otherwise flat site, as well as providing a well drained area for those plants that are sensitive to damp or waterlogged soils. In both cases the exposed rocks can provide an enjoyable place to sit and contemplate your garden, but be careful that any plants you might use near the rocks will not hide the rocks when they grow larger.
6. It is possible to simulate the effect of rocks in a garden, using artificial rocks, made of concrete. Artificial rocks, if created properly, will look just as real as the genuine item. Components used in the surface layer will create both a texture and color which simulates the appearance of natural rock formations. This type of work has a number of advantages over working with real rocks, such as the ability to create any shape and size of rock you desire, including crevices for planting, water courses, or pools. You do not have the work of moving heavy boulders about (though mixing concrete can be heavy), and you are not damaging natural environments by removing rocks which may be an integral part of natural ecosystems.
An alternative method is to include some gravel in the render. This can either be left to harden to give a pebbly granite like appearance or the gravel can be scraped away before the surface has hardened to give a pitted sandstone like appearance. A third method is to include some rock salt crystals in the mix, which can be dissolved out by water when the surface has hardened. Naturally coloured sands and gravels should be used to give the best results.
If you are going to plant close to rock work where concrete or mortar has been used, be aware that the concrete and mortar is alkaline (a high pH), and will affect the pH of the soil around it as chemical components leach out of the cement. In sandy soil, the effect may wash away through the soil after 6 months or so, however, it is wise to test the pH, and perhaps compensate for this problem by washing the surface of the rocks a few times with a 50/50 solution of vinegar and water.
As with the rocks that you choose careful plant selection is also very important to get the best results. A good idea is to have a close look at naturally occurring rocky areas to see what types of plants are growing well in such situations. This will help you to select plants that will fit the particular rocky theme you are creating. Be careful to choose varieties that will not completely hide your rocks as they grow larger. Some plant varieties have proven generally successful in rockeries.
20 hour short course