Pruning is a horticultural practice that alters the form and growth of a plant. Based on aesthetics and science, pruning can also be considered preventive maintenance. Many problems may be prevented by pruning correctly during formative years for a tree or shrub.
Reasons for pruning
Prune to promote plant health
Remove dead or dying branches injured by disease, severe insect infestation, animals, storms, or other adverse mechanical damage.
Remove branches and branch stubs that rub together.
Avoid topping trees. Removing large branches leaves stubs that can cause several health problems. It also destroys the plant’s natural shape and promotes suckering and development of weak branch structure.
Prune to maintain plants; intended purposes in a landscape, such as:
encouraging flower and fruit development,
maintaining a dense hedge, or
maintaining a desired tree form or special garden forms.
Prune to improve plant appearance
Appearance in the landscape is essential to a plant’s usefulness. For most landscapes, a plant’s natural form is best. Avoid shearing shrubs into tight geometrical forms that can adversely affect flowering. Alter a plant’s natural form only if it needs to be confined or trained for a specific purpose. When plants are pruned well, it is difficult to see that they have been pruned! Prune to:
control plant size,
keep evergreens well-proportioned, or
remove unwanted branches, waterspouts, suckers, and undesirable fruiting structures that detract from plant appearance.
Prune to protect people and property
Remove dead branches.
Have hazardous trees taken down
Prune out weak or narrow-angled tree branches that overhang homes, parking areas, and sidewalks — anyplace falling limbs could injure people or damage property.
Eliminate branches Eliminate branches that interfere with street lights, traffic signals, and overhead wires. REMEMBER, DO NOT attempt to prune near electrical and utility wires. Contact utility companies or city maintenance workers to handle it.
Prune branches that obscure vision at intersections.
For security purposes, prune shrubs or tree branches that obscure the entry to your home.
Pruning begins at planting time
Pruning is really the best preventive maintenance a young plant can receive. It is critical for young trees to be trained to encourage them to develop a strong structure. (See Figure 1 on page 2)
Too many young trees are pruned improperly or not pruned at all for several years. By then it may become a major operation to remove bigger branches, and trees may become deformed.
At planting, remove only diseased, dead, or broken branches. Begin training a plant during the dormant season following planting.
Prune to shape young trees, but don’t cut back the leader.
Remove crossing branches and branches that grow back towards the center of the tree.
As young trees grow, remove lower branches gradually to raise the crown, and remove branches that are too closely spaced on the trunk.
Remove multiple leaders on evergreens and other trees where a single leader is desirable
Pruning young shrubs is not as critical as pruning young trees, but take care to use the same principles to encourage good branch structure.
When planting bare root deciduous shrubs, thin out branches for good spacing and prune out any broken, diseased, or crossing/circling roots.
When planting bare root deciduous shrubs for hedges, prune each plant to within 6 inches of the ground.
Newly planted shrubs require little pruning if they were container-grown or were dug with a soil ball.
Pruning large established trees
Leave the pruning of large trees to qualified tree care professionals who have the proper equipment. Consider the natural form of large trees whenever possible. Most hardwood trees have rounded crowns that lack a strong leader, and such trees may have many lateral branches.
The three most common types of tree pruning are:
Crown Thinning — selectively removing branches on young trees throughout the crown. This promotes better form and health by increasing light penetration and air movement. Strong emphasis is on removing weak branches. (Don’t overdo it on mature trees.)
Crown Raising — removing lower branches on developing or mature trees to allow more clearance above lawns, sidewalks, streets, etc.
Crown Reduction — removing larger branches at the top of the tree to reduce its height. When done properly, crown reduction pruning is different from topping because branches are removed immediately above lateral branches, leaving no stubs. Crown reduction is the least desirable pruning practice. It should be done only when absolutely necessary.
Proper branch pruning
To shorten a branch or twig, cut it back to a side branch or make the cut about 1/4 inch above the bud.
Always prune above a bud facing the outside of a plant to force the new branch to grow in that direction.