The main reason people plant hedges is to give them privacy from their neighbours or to screen out the adjoining street or some feature in the vicinity. The purely functional purposes of a hedge can be achieved by growing large evergreen shrubs which require relatively modest maintenance through the year. These are often referred to as informal screens.

A "hedge" in the sense that I'm using here though, refers to a line of shrubs that are trimmed regularly into the architectural form of a wall -- a green wall in fact. Growing a finely sheared hedge is one of the most labour intensive and difficult tasks in gardening, and should be employed therefore when there is a specific design reason for doing so. Here are some of the design questions that a hedge, as opposed to a screen of bushes, can answer.

* A hedge gives a sense of order to the garden. It does not necessarily have to mean extreme formality, and can fit into a relaxed if well defined design. Of course a hedge is not a "natural" element in the garden, but then neither is a wall or a seat.

* A sheared hedge forms an ideal backdrop to focal points such as a mass of flowers, a water feature, or a sculpture. In good design, the "support" elements are as important in creating the composition as the "star" features.

* It is the preferred solution in small gardens where free growing shrubs are liable to take up too much width.

Here are some tips for choosing the right species for your hedge.

* The plant should be evergreen and not deciduous. Remember that some plants are not naturally deciduous, but drop their leaves in response to low temperatures. Make sure your chosen plant will remain green during the winter as well.

* It's best to choose species with a relatively fine leaf texture. Course or large leaved shrubs tend to look worn and ragged after shearing.

* Dark to medium green is the best foliage colour. Variagated or purple coloured leaves contradict one of the main ideas of the hedge, namely to serve as a quiet background to focal points of interest. Coloured leaved plants should be used sparingly in the garden.

* Beware of plants that are overly rampant in their growth habit. It might double or treble the amount of shearings through the year. This last point can also have implications for your relationship with your neighbours, because one of the definite drawbacks of growing a hedge, is the noise caused by the mechanical hedge trimmer.

About the author - Jonathan Ya'akobi I've been gardening in a professional capacity since 1984. I am the former head gardener of the Jerusalem Botanical Garden, but now concentrate on building gardens for private home owners. I also teach horticulture to students on training courses. I'd love to share my knowledge and experience with you. So you're welcome to visit me on www.dryclimategardening.com