Garden edges, whether flat or raised, are primarily used to contain garden beds, but they are also an integral part of the garden landscape and should be planned accordingly.

Planning garden edges
Begin by drawing a detailed plan of your house and land. Each line that you draw will require some form of edge. It may be a flat edge (often a mowing strip), a raised kerb to retain garden or lawn or to control the flow of water, or a raised garden bed.

Next, you need to decide on the edging material. Consider the style of your home, the degree of formality required, the amount of money you have to spend and how readily the material is available.

As well as the materials discussed below there are less permanent materials, such as plants or the wire borders so popular with Victorian and Edwardian gardeners.

Bricks, pavers and tiles
Dry-pressed house bricks, which have a `frog' (a depression) on one side, are better for edges than extruded bricks, which have holes running right through the brick.

Raised brick edges can sit directly on the soil, but to prevent sideways movement they are: best contained on one side by a solid surface and on the other by a buttress of concrete.

Clay pavers are used for flat edges such as mowing strips and are laid on the flat, while terracotta tiles are used for raised edges and can be positioned in straight, curved or geometric lines. Like bricks, they are best supported by a solid surface and concrete buttress.

Stone
Stone makes an excellent hardwearing edging for the garden. It can be cut into regular shapes and the blocks butted closely together, or mortared as for brickwork. If the blocks are laid flush with the ground, a mowing strip will not be necessary. Undressed stone can be laid with or without mortared joints.

Concrete
Concrete can be used to make edgings of any shape or height. It has traditionally been neutral in colour, but the use of oxides to colour concrete is increasingly popular. Concrete strips can also be stamped or stencilled in a variety of patterns.

Precast concrete strips are available from most landscape supply centres.

They are most suitable for straight edging where lengths can be butted together. Other concrete products, such as cobblestones and pavers, are laid in the same way as bricks.

Timber
The simplest form of timber edging consists of lengths of timber (treated pine or durable hardwood) laid horizontally on edge and held in place by timber or metal pegs. When laid horizontally, such timbers are suitable only for straight edging. For curved edges, install these vertically, stacked closely side by side. They can be cut off in a level line or the height can be staggered to create a one up, one down effect.

Old (recycled) and new railway sleepers make ideal edges. They are heavy to move but are strong and fairly durable. Their own weight is usually enough to hold them in place, whether bedded at ground level or raised to create an edge.

Raised garden beds
Raised beds are used to create different levels within the garden, either for aesthetic reasons or to give greater control over growing conditions. Unless you have free-draining, sandy soil you will have to make provision for drainage, usually by making weep holes just above ground level every 600mm or so. It is also a good idea to place a 100mm deep bed of crushed rock, tile or broken brick in the base of the bed before filling it with soil. Check with your local Council on the height a DIYer is allowed to build without engineering details.

Source: Garden Edges & Retaining Walls (Murdoch Books)