Pruning Shrubs & Trees

• Pinch or cut off growing tips in the spring to force shrubs into bushier, more compact forms.
• The flowering of some shrubs can be enhanced by pinching. Rhododendrons and azaleas, for example, will produce more flowers if crowded buds are thinned by pinching in the fall.
• Pinching off spent flowers, called deadheading, can encourage bud formation as well as directing energy that would otherwise be spent on forming seeds toward roots and shoots. (Unlike many annuals, few flowering shrubs will bloom a second time in a year if deadheaded.)
• Cutting more than just the growing tip is called heading back. Stems are usually headed back to a lateral bud. Cutting whole stems back to the plant's crown or severing lateral branches at the crotch where they arise is called thinning.
• Stems or branches that cross the center of a bush are often headed back or thinned to allow in more light and air, reducing incidences of diseases that breed in the humid conditions of dense growth. Similarly, removing a stem that rubs on a neighbor eliminates a common cause of damaged tissue.
• Stems or branches may be headed back to encourage branching into a particular area. Find a bud facing the direction you want a branch to grow and cut just above it.
• New shoots arising at the base of stems or from roots are called suckers. A few may be desirable; many can produce a thicket. Cut them off flush with the stem base; pull up those sprouting from roots.

Rejuvenation:
Some shrubs can be pruned heavily each year in order to produce robust new growth the following growing season. Spirea, plumbago, and others are often cut back almost to the ground. Other shrubs may be cut back to old wood or to just a few buds on new wood. (Some shrubs will die back to the ground in colder climes but renew themselves each spring. Cut these to the ground in the winter or early spring.)

Heavy pruning can also bring new life to overgrown or tired shrubs. Some shrubs, such as malionia, may be cut almost to the ground. Lilacs and cotoneaster, on the other hand, can be renewed by cutting stems to several feet or longer. You can renew a shrub in stages, cutting one-third of the stems back hard one year, another third the next year, and the remainder in the third year. Sometimes you can nurture selected suckers as replacement stems.

Heavy pruning can be risky. Certain plants, including a number of conifers, do not renew from old wood. Before embarking on rejuvenation, consult with an expert to determine the best method.

PRUNING TREES-
A well-formed tree chosen with the conditions of the site in mind, planted correctly, and watered and fed appropriately should require little pruning when young and even less as it matures. This is particularly true of conifers, which may not need the attention of a pruning saw for years.

In many ways, trees are no more difficult to prune than shrubs, and many of the techniques are the same. What complicates matters for tree pruning is size-removing a 6-in.-diameter branch growing 30 ft. above the ground can be both difficult and dangerous. We urge you to call on professional arborists for such tasks. There is still much you can do while standing firmly on the ground.

When to prune:
As for shrubs, remove dead, damaged, or diseased wood as soon as possible. Likewise, if flowers are one of the tree's attractions, prune according to whether they bloom on old wood (prune after flowering) or new wood (prune in late winter or early spring). In general, late winter is a good time to prune. Deciduous trees have yet to leaf out, making it easy to see branching patterns. Pruning wounds have a full growing season to close, and new growth induced by pruning will be well formed and ready for the rigors of winter.

Some trees, such as maples and birches, "bleed" if pruned when sap is rising, increasing the chances of infection. Other trees are also more susceptible to particular diseases if pruned at certain times of the year, so it pays to consult with an expert before doing any major pruning on a tree you're not sure about.

How to prune:
For trees, pruning ranges from pinching off buds with your fingertips to removing huge branches with a chain saw. Although the scale may be different, the purposes of pruning are the same as those we've discussed previously.

• Pinching and heading back are useful techniques for affecting the shape of young trees. If you'd like to encourage branching into a particular area, trim just above a bud facing in the desired direction.
• You can open a tree to air and sun by thinning overcrowded branches and by removing those that cross the center.
• Trees characterized by a columnar shape often have a dominant central trunk, called a leader. Oaks, pines, and spruces are good examples. If these trees have two leaders when young, you can trim the second leader back to its base (best for conifers) or cut it back by half its length to ensure that the tree develops the desired shape.
• Do not cut off, or "top," the central leader of a columnar tree. The sad results of such pruning can be seen wherever power companies have "pruned" trees away from their lines. Better to remove the tree and plant one that won't grow so tall.
• Sometimes mature branches develop unattractive thin vertical shoots called water sprouts. Remove these by cutting flush with the parent branch.
• Occasionally, you'll want to remove a larger branch, perhaps to create headroom, to allow more sunlight beneath the tree, or to improve its general appearance. To do so, make a series of cuts to avoid tearing. Don't cut flush with the trunk, but instead cut along the branch collar, a swelling at a branch's point of origin.
• Research seems to show that wound dressings cause as many problems as they prevent. When cuts are made properly, a healthy tree is able to close the wound and protect itself from disease.