When trimming a shrub, the goal is to make it look like it hasn't been trimmed. Pruning cuts should be hidden inside the plant where they will be covered by remaining leaves. Once the injured, diseased and dead branches have been removed from the shrub, work on the shape of the shrub can begin. Trim the shrub so that it will fit in with the design of the lawn. A formal landscape usually is filled with shrubs in geometric shapes, while an informal space benefits with shrubs that need less maintenance and are trimmed simply to keep them healthy and contained.
Heading Back a Shrub
Many gardeners trim shrubs by using the heading back method. This is cutting back the ends of the branches or new twigs, on a slight slant, to the point of a node or about a quarter inch above a bud. New growth will grow in the direction the top bud faces. Heading back causes new growth on the outer part of the shrub, but the new growth is so thick that the shrub interior doesn't get enough light and the foliage thins out. The shrub will soon look spindly and top heavy.
Thinning a Shrub
Many experienced gardeners prefer thinning to heading back the shrub. Encourage new growth of the shrub by cutting branches back to the side branch or even the main trunk of the plant. Thinning not only reduces the size of the shrub, but it gives it a fuller look, more attractive look.
Pruning an Overgrown Shrub
Shrubs often grow larger than intended, crowding other plants or interfering with the landscape simply by overgrowing their space. Narrow leaf evergreens may have to be transplanted, but broadleaf shrubs can be contained to an appropriate size by a method called renewal pruning.
Before the first growth begins in the spring, cut the shrub back drastically. Achieve a basis for the desired shape of the bush by cutting individual branches down to within 6 to 12 inches of the ground. Once the new growth is about 6 to 12 inches, lateral branching can be encouraged by pruning the tips.
Shrubs Trimmed to Look Like Trees
Shrubs with fast-growing trunks can be trimmed to look like trees by removing the bottom lateral branches.
If more than one truck is desired, choose sturdy branches that grow upright, and cut everything else back to the ground. The remaining upright stems will serve as the trunks. Remove all lateral growth below 4 feet.
Complete the trimming by removing any branches that cross each other. A thinner, treelike appearance can then be achieved by removing any inward growing lateral branches.