Hedges serve an important purpose in the garden. They delineate areas with a garden, screen out undesirable views and can also mark boundary lines. They can also act as a windbreak or mark the edge of a path. Both evergreen and deciduous shrubs are suitable for hedges. It depends on your needs. If you use your garden space mainly in the summer and need only seasonal screens, deciduous shrubs may be adequate. Even so, frequently pruned deciduous shrubs will form a dense tangle of twigs which provide a winter screen. Evergreen shrubs are effective as year round hedges. Hedges can be either formal or informal. Either way, hedges should be dense and compact.
The easiest way to plant a hedge is to dig a trench. When planting be sure the root ball is level with the existing grade of the garden. The plant spacing will vary. Dwarf boxwood, for instance, should be spaced about 8 inches apart. Larger plants, such as privet, can be spaced 18-30 inches apart. Large tree evergreens should be planted 6 feet apart.
With deciduous plants, cut back the plants to within 6-8 inches of the ground immediately after planting. This allows the roots to become established and produces fuller top growth. Evergreens should be given a preliminary shaping at planting time.
Most people make the mistake of allowing the hedge to grow too tall before cutting. An ideal hedge is well branched to the ground. As a general rule, stems should be cut back at least six inches every time they grow a foot. The sides of the hedge should be cut proportionally. Wide tops tend to shade out the lower branches resulting in leggy growth.
Hedges of deciduous shrubs generally require pruning two times each season. Once when the plants are at their desired height and once later in the season. Rapidly growing shrubs, such as privet, may require more pruning to keep the hedge‘s shape. Prune when the new growth has reached about six inches. It is essential that blooming time be considered when pruning flowering hedges.
Narrow-leaved evergreens, such as arborvitae, hemlock or yew, require less frequent pruning. Don’t be afraid to prune these heavily. For pines, spruces and firs, remove the lead bud or shoot on the tip of every branch each year by snipping. Then shape into a formal effect with a pruning shears.
Broad-leaved evergreens such as the hollies should be pruned just enough to keep the branches in line. Always cut back to side branches or buds. Usually a pruning in the spring before growth starts and a lighter pruning later on to straighten up the hedge lines is sufficient.
Rejuvenation of evergreen hedges is difficult. Many evergreens will not re-grow if cut back to where no foliage is present on the stem. In such a case it is advisable to start over.
If the hedge is deciduous, you have two choices. If they're not too overgrown, cut back the shrubs a bit below the desired final height. This will allow a new twiggy outside layer to form which may be pruned to the desired size in several stages. If the hedge is badly overgrown, some plant species may be completely cut back to within 6-12 inches of the ground. Train the new growth as if you a new planting.