This is even quicker to carry out than cutting a grass edge with shears. It is not only an advantage to have a flat line of stone where levels are different but also between the lawn and a bed, particularly an herbaceous border where plants near the edge, such as Oenothera missouriensis, Nepeta x faassenii and Geranium cultivars, can sprawl unrestricted. In a mixed border, too, where flat or cushion-like shrubs such as Cistus, Halimium, Genista and Hebe can be planted they will be given a different dimension than when restrained to keep within the bounds of the grass edge. SITING PATHS If a path is needed for getting from one part of the garden to another, along the boundary of the lawn might be a good place for it to be sited; it would be both functional and aesthetic. But unless a path is actually needed there is little reason for its existence, taking up space and reducing the garden area. If it is necessary, however, and the above suggestion is not suitable, another advantageous position for it is at the back of a border so that it is between this feature and a hedge or fence. The reason for this is fourfold. First, it does not divide the garden and so direct the eye to a place where there is perhaps no view-point. Secondly, if a wall or fence forms the boundary this feature can be used to train fruit trees or ornamental shrubs and climbers. A space i8in(45cm) wide is usually enough to leave between the path and the boundary, but even if it is not intended to do any planting against the wall, the edge of the paving should be at least 9,in(23cm) away to allow shoulder room, otherwise it is only possible to walk on the outer side of the path. Thirdly, if the boundary is formed by a hedge it is easier to pick up the trimmings from a path. Fourthly, another good reason for so siting a path is that the ground within a yard or two (1 to 2m) from the hedge is probably the least fertile. Roots from the hedge compete with plants or shrubs in the border and there is sometimes a problem of perennial weed roots encroaching from outside the boundary. This invasion can be controlled by digging a narrow trench close to the fence or hedge to a depth of i8in(45cm) to 2ft(6ocm) and burying, in a vertical position, with the tops just below soil level, sheets of old roofing material such as are usually available from a builder or demolition firm. All weeds can then be eradicated from the bed and there will be no further spread, unless, for instance, if ground elder or couch grass has entered into clumps of perennial plants, such as paeonia and asters. The most effective way then to ensure that no trace of such roots remain is to dig up the plants in the winter, wash out all the soil and pick out the weed roots before replanting the perennials in a nursery bed for COVERING HIGH BANKS, CLIFFS AND TERRACING The use of climbing plants as a cover for banks is generally neglected even though in some more difficult situations it is an easy and attractive way of overcoming the weed problem.