Deciduous shrubs are never static. Soft new leaves unfurl in spring; soon flowers bloom, fade, and then ripen into glossy berries or handsome seedpods. Foliage colors in autumn and bare branches in winter send playful shadows across the snow. This diversity is part of the appeal of deciduous shrubs; when properly pruned, they put on an outstanding show throughout the seasons.
The way shrubs are pruned influences their shape, size, and flowering characteristics. Although proper shrub pruning techniques are not difficult to learn, information on these techniques may be hard to come by. Instructions on how to apply lawn fertilizers appear on every fertilizer bag; each pesticide container is labeled with specific directions for its use. There are adequate instructions in many gardening books for digging holes and planting bare-root, balled-and-burlapped, and container-grown plants. But seldom are pruning instructions attached to a new plant or to a pair of pruning shears. Furthermore, many older manuals on pruning are now outdated. This section intends to make shrub pruning an easy matter; it explains the correct ways to prune deciduous shrubs and hedges and to rejuvenate old, neglected specimens.
Growth Characteristics of Shrubs
Deciduous shrubs have distinct shapes: weeping, rounded, oval, upright, spreading, and irregularly shaped shrubs can be found in most gardens. During the growing season it is primarily foliage that determines whether a shrub is coarse-, medium-, or fine-textured. When the leaves have fallen, bark and stems define the texture. An appealing planting design can be created by contrasting or echoing the texture and shape of one shrub with another. Prune to emphasize or minimize textural and shape differences.
Professional landscape designers advocate growing shrubs in groups or masses and allowing them to blend together into a bold and striking planting. Pruning methods detailed here teach how to control size while maintaining the natural shape of each shrub within a grouping. The shrubs blend together visually when they are pruned by thinning the branches.
Deciduous shrubs are best if left natural looking; avoid shearing them into formal shapes unless they are used as hedges. Whether deciduous or evergreen, individual shrubs sheared into formal shapes stand isolated from one another. This look may suit fine-textured evergreens, but the bolder look of most deciduous shrubs is better suited to a more naturalistic pruning technique. When flowering shrubs are sheared, the flowers become so crowded that they are seen as a mass of color rather than as separate colorful blossoms with appealing shapes and outlines.
Correctly pruned shrubs look as if they have not been pruned at all. If a deciduous shrub looks as if it obviously has been pruned, probably too much has been done to it. If there is no reason for a pruning cut, don’t make it. Not all plants need pruning, either. Slow growers and shrubs with a well-proportioned framework are nearly care-free.
Pruning Techniques for Deciduous Shrubs
Before pruning a shrub, consider its mature height, natural branching characteristics, and distinctive shape. Proper thinning maintains that shape regardless of the age or size of the shrub. Thinning also allows light to penetrate a shrub mass and create interesting patterns.
When properly pruned, deciduous shrubs consist of stems of various heights and ages, which arise directly from the ground. Removing some of the oldest stems each year or two continually makes room for new shoots to emerge. Meanwhile the remaining stems, benefiting from increased exposure to sunlight, grow and bloom more vigorously. This type of pruning gradually renews a shrub before it becomes so crowded with old stems that drastic measures are needed to improve it.
Use long-handled loppers to remove stems at or near ground level. Small curved pruning saws may be needed if the stems are larger than 1 inch in diameter or very woody. Remove one fifth to one third of the oldest, tallest, and darkest branches.
Cut the branch in two steps. Begin by making a heading cut that leaves a stub about one third of the former length. After pulling out the cut branch from the mass of branches, prune the stub as close as possible to the ground. The stem is easier to remove if pruned in two steps rather than cutting the entire stem to the ground at once. Do not leave long stubs since these rarely produce satisfactory new growth. More often, the stubs die back to the ground.
Occasionally branches cross and rub, a common occurrence when one branch grows too tall. The weight of the overgrown branch forces it to sag down onto a branch below. Remove the heavy branch with loppers or hand pruners and allow a younger, more upright stem to take its place.
When branches are headed rather than thinned, new growth will often originate from an inward-facing bud. The resulting branch heads into the center of the shrub, disrupts the natural growth pattern, and rubs against other branches. It’s best to cut such a branch off at its origin even if it leaves an apparent hole in the foliage; new growth will soon fill in.