Hedges

Quick Facts...

• Planting stock for hedges should be thrifty, healthy and uniform.
• Young trees or shrubs are preferable for hedge planting. Early spring planting is best for hedges in the Rocky Mountain region.
• Careful pruning is necessary to produce desired shape and density.
• Properly pruned hedges should be slightly narrower at top than bottom to prevent shading out of lower branches.

Selection

Base the choice of planting stock on the health and thriftiness of plants. Stock should be free from insects and disease.

Some dealers may offer special hedge materials at bargain prices, but such plants often are stunted and culled from regular nursery stock. Though they may be inexpensive, they are a poor investment.

Use only normal, well-grown plants for hedges. They should be of similar size, shape, root development and foliage color, because their uniformity influences the appearance of the ultimate hedge to a considerable extent.

Planting young trees or shrubs usually is preferable to using older stock. In planting a deciduous hedge, select one-year-old seedlings or cuttings. These are available as dormant, bare-root material in early spring. For an evergreen hedge, it is best to use container-grown or balled and burlapped stock.

Planting

Early spring planting is preferable to fall planting in the Rocky Mountain region.

Planning for plant spread is the first step in planting. Do not place young plants too close to a wall, walk or driveway that doesn't allow space for spreading. The spread of a hedge will depend on the species used. Unclipped hedges (informal) require more space than those that are sheared for formal effects. The average hedge 3 to 5 feet high will be 3 to 5 feet wide. This means the plants for such a hedge should be set 18 to 24 inches from a property line, wall, driveway or walk.

Digging a trench of adequate size and desired length is the next step in planting. After deciding the proper location of the hedge, prepare a trench deep enough to accept the root system for the plants and long enough to place them all at the same time.

Spacing of plants also will depend on the species used. Set dwarf plants, such as the dwarf arctic willow, about 6 inches apart. Space plants for medium height hedges, such as privet or forsythia, about 12 inches apart. Plants for hedges composed of tree species usually are spaced 18 to 30 inches apart.

Complete each step of the planting procedure at one time. After digging the entire trench, line out the young plants at the proper spacing and quickly backfill the trench with soil so that the roots will not dry out. Then water the plants well and prune.

Pruning

Figure 1: A) The proper way to shape a hedge (end view). B) Other shapes that can be used that will still result in dense foliage all the way to the ground line.

Figure 2: A) A hedge improperly shaped (end view). The wider top has shaded out foliage at the base, resulting in a "leggy" look. B) Other shapes in common use that result in a thin, leggy hedge.

Prune back after planting according to the amount of branching of the planting stock. Prune very small, unbranched stock to within three or four inches of the ground. Prune moderately branched, larger material 10 to 12 inches from the ground, and well-branched stock 18 to 24 inches from the ground. More or less pruning may be necessary depending on the condition of the original stock.

Pruning to train the hedge during early development is important to its future shape and density.

After planting and pruning back, allow plants to develop new growth until about the end of June. Then cut back the growth again by removing approximately two-thirds of it in order to force plants to develop more side branches. Depending on the vigor and species of the plants used, a third and even a fourth pruning can be done before frost.

When the plants begin to form a dense hedge, shape the hedge so that it is narrower at the top than at the bottom (see Figure 1). This treatment allows more light to penetrate the lower branches, thus reducing the amount of "legginess" that can result when lower branches are shaded by upper ones (see Figure 2).

Shear hedges that are oriented in an east-west direction so that the side facing north is sloped more than the side facing south. This allows more light to penetrate the shaded north side and results in a more uniform appearing hedge.

Periodic pruning needed by the hedge plants, once they have been trained into a hedge, will depend upon the type of hedge, whether it is to be formal or informal and its ultimate size.

Informal hedges require less frequent pruning, but branches growing in an undesirable direction may need to be removed occasionally. Also, periodic pruning might be necessary to encourage dense, screening growth.

Shear vigorous plants, such as privet and arctic willow, several times during the growing season if they are to be maintained as a formal hedge.

Pest Control

Attacks by insects or disease can be severe and result in open places in the hedge.

Immediately treat insect pests, particularly aphids and infestations of spider mites, with appropriate pesticides. (For more information see fact sheet 5.507, Spider mites, and 5.511, Aphids on shade trees and ornamentals.)

Foliage diseases, such as mildew or leaf spot, generally are not serious if preventive fungicides are applied during the growing season. Disease of the main trunk in hedges, such as the numerous types of canker diseases, usually are more difficult to control. They often necessitate removing portions of a hedge and replanting with healthy material.

¹ Colorado State University Extension landscape plants specialist and professor (retired); horticulture. 9/92.

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