Hedges become part of the landscape as well as setting limits to it; they are more attractive than any mere fence. Like fences, they can provide shade for perennials or shelter plants against winter winds. They may not be as effective at obstructing passage as fences, but even a deciduous hedge will delay large dogs and small children. Many plants can make a hedge, depending on its purpose and location.
Privacy hedges act as barriers to sight, sound or movement. Evergreen shrubs make dense, year-round hedges for privacy; arborvitae and cedars can grow and form tall screens. Blue-green upright Rocky Mountain and Chinese junipers are evergreens that must be kept short by annual pruning. Compose privacy hedges of two rows of shrubs: one, a taller evergreen row and a second deciduous row of holly, euonymous or other shorter plants. White fir and Eastern white pine evergreen trees make soft backups for shrubs like hollies, barberry or firethorn that have bright foliage or berries. Hawthorns and barberry shrubs make convincing barriers. Douglas firs and blue spruce make effective wind-break hedges.
Use flowering and berry-setting shrubs for hedges to provide color in the garden and for contrasting foliage shapes and colors. Shrub roses have become popular, and newer, disease-resistant varieties are hardy and can be pruned once in late winter. Cherry laurel and butterfly bush both feature tall white panicles of summer flowers. Dwarf magnolias and magnolias that are pruned to encourage branching make an interesting hedge. Flowering shrubs are often deciduous; lilacs, forsythia and wegelia should be trimmed after blooming in spring to keep them compact. Hydrangeas and spireas provide showy displays but their spreading habits make them useful only for purely decorative hedges. Rhododendrons, euonymous and mountain laurel will tolerate shade. Avoid planting hedge shrubs near maple trees; they cannot compete with the maple's shallow roots for water and nutrients.
Formal gardens use geometrically trimmed hedges to define spaces and sections of the garden. Taxus, hornbeam, beech, boxwood and laurel shrubs are favorites for formal gardens because they shear easily and recover quickly with new growth. Alpine currant and common privet are hardy to USDA zone 2. Common myrtle and wax-leaf privets will thrive in Southern gardens to zone 9. Japanese holly combines the best of both worlds, growing from zone 2 to zone 9; it has a naturally mounded growth, but this holly's tough leaves necessitate hand pruning rather than shearing.