A hedge is a line of closely spaced shrubs and bushes, planted and trained in such a way as to form a barrier or to mark the boundary of an area. Hedges, especially those used to separate a road from adjoining fields or one field from another, and of sufficient age to incorporate small trees, are also frequently known as hedgerows. It is also a simple form of Topiary.
Many hedgerows separating fields from lanes in England,Ireland and the Low Countries are estimated to have been in existence for more than seven hundred years. The root word of 'hedge' is much older: it appears in Old English, in German (Hecke), and Dutch (haag) to signify 'enclosure', as in the name of the Dutch city The Hague, or more formal 's Gravenhage, meaning The Count's hedge. Charles the Bald is recorded as complaining in 864, at a time when most official fortifications were constructed of wooden palisades, that some unauthorized men were constructing haies et fertés – tightly interwoven hedges of hawthorns.
The nineteenth century Great Hedge of India was probably the largest example of a hedge used as a barrier. It was planted and used to collect taxes by the British.
If hedges are not maintained or only trimmed repeatedly, gaps tend to form at the base over many years. In essence, hedgelaying consists of cutting most of the way through the stem of each plant near the base, bending it over and interweaving it between wooden stakes. This also encourages new growth from the base of each plant. Originally, the main purpose of hedgelaying was to ensure the hedge remained stock-proof. Some side branches were also removed and used as firewood.
The maintenance and laying of hedges in such a way as to form an impenetrable barrier for farm animals is a skilled art. In Britain there are many local hedgelaying traditions, each with a distinct style. Hedges are still being laid today as they are not only beautiful and functional but they also help wildlife and protect against soil erosion.
Hedges of clipped trees forming avenues are a feature of 16th century Italian gardens such as the Boboli Gardens in Florence, and of formal French gardens in the manner of André Le Nôtre, e.g. at Versailles. The 'hedge on stilts' of clipped hornbeams at Hidcote Manor Garden, Gloucestershire, is famous and has sometimes been imitated.
Hedges below knee height are generally thought of as borders. Elaborately shaped and interlaced borders forming knot gardens or parterres were fashionable in Europe during the 16th and early 17th centuries. Generally they were appreciated from a raised position, either the windows of a house, or a terrace.
Clipped hedges above eye level may be laid out in the form of a labyrinth or garden maze. Few such mazes survived the change of fashion towards more naturalistic plantings in the 18th and 19th centuries, but many were replanted in 20th century restorations of older gardens. An example is behind the Governor's Palace, Colonial Williamsburg, Virginia.
Hedges and pruning can both be used to enhance a garden's privacy, as a buffer to visual pollution and to hide fences. A hedge can be aesthetically pleasing, as in a tapestry hedge, where alternate species are planted at regular intervals to present different colours or textures.