Pruning and trimming are two techniques homeowners perform when taking care of their gardens. Trimming usually applies to maintaining small shrubs or hedges, while horticulturists use pruning for trees and shrubs. Both horticulture terms are used interchangeably but utilize different types of equipment and have different times for implementation. The end result of trimming and pruning are healthy and aesthetically appealing trees, shrubs and hedges.
The idea behind pruning is to prevent loose or dead branches from harming other plants or people. Removing these branches allows the tree's flowers and fruit to flourish. Pruning is not meant to stunt growth, but to stimulate the tree. Eliminating diseased or pest infested branches are other reasons gardeners prune their trees. Gardeners also prune if they want their tree to have a particular shape for aesthetic purposes. Two forms of pruning, pollarding and topiary, cause trees to take on unnatural forms. Pollarding is the practice of pruning annually to produce new shoots on an annual basis. Topiary is the art of shaping trees into an animal or geometric shape.
Trimming applies to tidying up a small shrub or hedge's appearance by removing overgrown branches. While pruning focuses on safety and a tree's health, gardeners usually trim shrubs and hedges for aesthetic purposes. However, excessive overgrowth is harmful since it reduces the amount of moisture and light a shrub receives, so gardeners should trim a shrub at least twice per year to prevent this from happening.
Two types of shears are available for pruning: hand shears and lopping shears. Hand shears are meant to be handled with one hand and are primarily used for removing small, easy to remove buds and leaves. Lopping shears have 1- to 2-foot long handles and are meant for cutting off thick branches. The lopping shear's design allows gardeners to exert more force while cutting. If a branch is too thick for both shears, gardeners resort to saws for pruning. Both types of shears are viable options for trimming shrubs and hedges. A hedge trimmer is used for trimming a hedge's branches. Electric and gas-powered hedge trimmers are available.
The required frequency for pruning or trimming varies among plant species. Spring flowering trees need pruning during late June, immediately following the trees' blooming cycle. Winter and spring are appropriate pruning periods for summer flowering trees, says the University of Maryland's Cooperative Extension program. The most appropriate periods for trimming hinges on a shrub or hedge's appearance, rather than its health or flowering cycles. According to the University of Arizona College of Agriculture and Life Sciences, gardeners should trim their hedges before excessive branch growth reaches 1 foot.