Garden planning Water features and rock gardens A water feature can involve still or moving water. For a moving water feature, a pump must be installed (which will need annual maintenance). The cabling must be laid by a qualified electrician. It is usual for the mains socket to be attached to the outside of the house (in a special housing) but it is possible for the switch to be inside the house. Never install a pond of any kind if the client has small children. A bubble fountain with a concealed reservoir may be an option in this case. Making any kind of water feature (with or without an associated rock garden) is hard work and time-consuming. However well you plan, some issues can only ever be resolved on site. Still water features Wildlife/informal pool A wildlife pool must be in full sun, ideally well away from overhanging deciduous trees that shed leaves into the water in autumn. To prevent overheating of the water in summer, the surface area should be at least 6m2 and the depth should be (at its lowest) at least 45cm. Allow a shelf to one side for growing marginal aquatics in pots. One side should slope gently and incorporate a ‘beach’ to allow mammals that may fall in to get out. The planting should include at least one deep-water plant with floating leaves (usually a water lily/Nymphaea) so that around 70% of the water surface is covered in summer. This keeps the temperature down and shelters frogs and other aquatic wildlife. Otherwise, the water in a wildlife pool is self-regulating – it does not need to be replaced, though it will be necessary to top it up from time to time during spells of hot weather in summer. Formal pool A formal pool (square, oblong, circular or oval in shape), sometimes used as the centrepiece of an Islamic garden, is often made of concrete (expensive, usually cast in situ). It may contain no plants but may be used to house fish (in which case, some oxygenating plants will be required as well as soil at the base). If no fish or plants, keep the water clear with a chemical agent. If used for fish, add a biological filter – this will keep the water pure but not clear. For clear water, add an ultraviolet water clarifier. (Filters are sometimes housed outside the water concealed by planting. A pump moves the water through the filter.) A fountain will help oxygenate the water. Moving water features A moving water feature requires a pump to lift the water and a reservoir. (In the case of a watercourse, the reservoir will be the lowest pool.) It is essential that the pump is sufficiently powerful to lift the water to the desired height and in an adequate volume – otherwise the water will not flow evenly. The water feature must be carefully constructed to minimise water loss – as much water as possible should be returned to the reservoir so that this does not
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have to be topped up too often. Most ready-mades do not have a sufficiently large reservoir. Moving water features can be made in shade. A gargoyle, lion’s head or mask cemented to a wall can spill water into a basin beneath in a courtyard garden. (Always be aware that a moving water feature, along with wind chimes, bonfires and barbecues, can drive the neighbours nuts.) Rock gardens Rock gardens are often made in conjunction with a pool. On a practical level, it allows you to deal with the spoil. A rock garden is made for growing alpines and other similar plants – small, low-growing, usually tuft-forming, hardy perennials (e.g. androsace, dianthus, phlox). These have a low nutrient requirement (so need little soil), are tolerant of drought and freezing temperatures, but must have swift drainage. Rock gardens are usually sited in full sun, but it is also possible to make a shady rock garden for growing ferns, small hostas and dwarf conifers. Making the rockery Dig over the site and remove all traces of weeds. If the drainage is poor, dig in some horticultural grit. Mound up the soil (if the ground does not already slope). Set the rocks into the soil, larger ones towards the base of the mound. One third to a half of each rock should be buried. Tilt the rocks slightly so that the water runs back into the soil or away from the plants – water should not drip onto plants below nor should they ever be sitting in water. Arrange the plants in the gaps among the stones, adjusting the angles of the stones as necessary. Water them well until they are established.
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