In gardening a hedge is a row of woody plants, generally of one species, used to demarcate spaces. If a mixture of small trees and shrubs is used instead, to keep people and animals from straying through pasture or cropland, the result is a hedgerow. Some hedgerows separating fields from lanes in England and the Low Countries are estimated to be over seven hundred years old. 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 capital of the Netherlands, The Hague.

Hedges may be clipped or unclipped. Typical woody plants for clipped hedges include boxwood, privet, yew, hemlock, arborvitae, barberry, holly, oleander, lavender, etc. An early 20th century fashion was for tapestry hedges, using a mix of golden, green and glaucus dwarf conifers, or beech and copper beech. Unclipped hedges take up more space, generally at a premium in modern gardens, but compensate by flowering. Rosa multiflora is widely used as a dense hedge along median strips of parkways. In mild climates, more exotic flowering hedges are formed, using Ceanothus, Hibiscus or Camellias.

Hedges of clipped trees forming allées 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 Notre, e.g. at Versailles. The 'hedge on stilts' of clipped hornbeams at Hidcote, 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.