There are two basic ways of pruning trees and shrubs: thinning and heading back. Thinning is the removal of a lateral branch at its point of origin or the shortening of a branch to a smaller lateral branch. Thinning serves to open a plant to sunlight and air and reduce the size and accentuate the natural form. In most cases, thinning cuts are preferable to heading cuts.

Heading back-also called cutting back, involves cutting a currently growing shoot or bud, or cutting an older branch back to a stub or a tiny twig. Pinching and shearing are forms of heading. With a few important exceptions, including pruning fruit trees to establish main framework branches, shearing hedges to keep them compact, and pruning roses for flower reproduction, heading is less desirable than thinning. The reason is simple: heading results in vigorous growth below the cut, usually from several buds. While a plant that has been headed does become more compact, its natural shape is ruined and will be difficult to repair. In addition, new growth is often weakly attached and prone to breaking.

There is a right way to make pruning cuts while there are several wrong ways. For the best results, slant the cut upward at about a 45 degree angle so that its lower point is even with the top of a growth bud.

Pruning to Shape:

Every plant has a natural shape. Before pruning, observe the plant's natural shape and prune it to allow this natural shape to continue to develop. Using thinning cuts, remove any excess growth that obscures the basic pattern or any growth that departs from the natural shape. Make the cuts above a bud or side branch that points in the direction you would like the new growth to take. Keep in mind that is better for the growth to be directed toward the outside rather than the interior. Try to eliminate branches that cross or touch one another.

Pruning for Flower Production:

Flowering shrubs bloom either from new growth or from old wood, depending on the plant species. To avoid cutting out stems that would give you a flower display, determine which sort of growth bears flowers. Most spring-flowering shrubs bloom from wood formed during the previous year. Wait until these plants have finished flowering before pruning them.

Pruning Conifers:

Conifers fall into two broad classes: (1)those with branches radiating out from the trunk in whorls (spruce, fir, and most pines); and (2)those that sprout branches in a random fashion (arborvitae, hemlock, juniper and yew). Pruning guidelines differ for the two groups. On the whorl-branching types, buds appear at the tips of new growth, along the lengthening new growth, and at the bases of new growth. You can cut back the new growth "candles" about halfway to induce more branching, or you can cut them out entirely to force branching from buds at their bases. Random branching conifers can be pruned selectively, headed back, even sheared; new growth will emerge from stems or branches below the cuts.