Pruning is one of the most important cultural practices in landscape management.
Proper pruning helps keep plants' attractive and vigorous and will add years to the plants usefulness.
Maintain plant health
Remove dead, damaged or diseased plant tissue to maintain plant health and vigor.
Prune to remove misshapen, crowded and rubbing branches and branches with narrow crotch angles. These pruning cuts eliminate problems before plant damage occurs.
Increase flowering and fruiting.
More flower buds will be formed for the following season if old flowers are removed when they lose their attractiveness, a practice called dead-heading.
Train plants to a particular size or shape, including hedge and espalier forms.
Rejuvenate old, overgrown shrubs and restore plant density, shape and vigor.
Large-habit plants in the wrong place, like hollies, privet and photinia planted in front of windows, should be replaced. When cut back or pruned severely, the large root system that remains helps these plants quickly resume their original size.
Only a few key tools are needed to prune correctly.
Invest in high quality tools and keep them sharp.
Sharp blades leave smooth cuts that heal faster and help reduce disease problems.
Types of Tools You'll Need
Hand clippers: For removing branches less than 1 inch (1.5 cm) in diameter.
Anvil clippersare used on dry old growth less than 1 inch (0.5 cm) in diameter and on plants that do not have hollow stems.
Hedge shears: For developing a formal, shaved or sheared appearance.
Hedge shears are the pruning tool most often used incorrectly and produce indiscriminate heading cuts.
Do not use shears on any shrub where a natural shape is desired.
Pruning saws: To remove 1 inch (4 cm) and larger diameter limbs.
Do not use a carpentry saw.
Invest in an arborist's saw that has a narrow, curved blade 12 to 15 inches (30 to 38 cm) long.
Some of the most effective pruning saws have saw teeth angled toward the handle that cut on the pulling stroke. Other saw blades have teeth designed to cut with both push and pull strokes.
A combination pole saw with pruners: This provides a handle that is 10 to 12 feet (3 to 3.6 m) in length for cutting difficult-to-reach branches.
Pole saws and pole pruners may be purchased as separate tools or as a combination tool.
Purchase a fiberglass pole handle and use extreme caution when pruning near electric lines to reduce risk of electrocution.
Electric, gas and battery powered pruners: Lightweight and powerful. Gas powered fixed- or variable-length pole pruners have a light, two-cycle engine connected to attachments that can include a small chainsaw blade, string trimmers or bypass clippers.
When to Prune
Pruning can actually be done at any time of the year; however, recommended times vary with different plants.
Pruning at the wrong time of the year does not kill plants, but continual improper pruning results in damaged or weakened plants.
Do not prune at the convenience of the pruner, but rather when it results in the least damage to the plant. There is little chance of damaging the plant if this rule is followed.
In general, the best time to prune most plants is during late winter or early spring before growth begins.
The least desirable time is immediately after new growth develops in the spring. A great amount of food stored in roots and stems is used in developing new growth. This food should be replaced by new foliage before it is removed; if not, considerable dwarfing of the plant may occur.
It also is advisable to limit the amount of pruning done late in summer as new growth may be encouraged on some plants. This growth may not have sufficient time to harden off before cold weather arrives resulting in cold damage or winter kill.
Prune plants damaged by storms or vandalism or ones with dead limbs as soon as possible to avoid additional insect and disease problems that may develop.
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.
Young trees pruned improperly or not pruned at all for several years may require heavy to remove bigger branches to prevent trees from becoming 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.
Container grown shrubs require little pruning.
When planting deciduous shrubs, thin out branches for good spacing and prune out any broken, diseased, or crossing/circling roots.
When planting deciduous shrubs for hedges, prune each plant to within 6 inches of the ground.
To avoid oak wilt disease do not prune oaks from April to October.
If oaks are wounded or must be pruned during these months, apply wound dressing or latex paint to mask the odor of freshly cut wood so the beetles that spread oak wilt will not be attracted to the trees.
To avoid increased likelihood of stem cankers, prune honey locusts when they are still dormant in late winter. If they must be pruned in summer, avoid rainy or humid weather conditions.
Prune apple trees, including flowering crabapples, mountain ash, hawthorns and shrub cotoneasters in late winter (February-early April).
Spring or summer pruning increases chances for infection and spread of the bacterial disease fire blight.
Autumn or early winter pruning is more likely to result in drying and die-back at pruning sites.
Some trees have free-flowing sap that "bleeds" after late winter or early spring pruning. Though this bleeding causes little harm, it may still be a source of concern.
To prevent bleeding, you could prune the following trees after their leaves are fully expanded in late spring or early summer. Never remove more than 1/4 of the live foliage. Examples include:
All maples, including box elder
Butternut and walnut
Birch and its relatives, ironwood and blue beech
Trees and shrubs that bloom early in the growing season on last year's growth should be pruned immediately after they finish blooming.
Shrubs grown primarily for their foliage rather than showy flowers should be pruned in spring, before growth begins.
Shrubs that bloom on new growth may be pruned in spring before growth begins.
Plants with marginally hardy stems such as clematis and shrub roses should be pruned back to live wood.
Hardier shrubs such as late blooming spireas and smooth (snowball) hydrangeas should be pruned to the first pair of buds above the ground.
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.
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.
Crown Cleaning - the selective removal of dead, dying and disease wood from the crown.
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.
Pruning Large Branches:
To remove large branches, three or four cuts will be necessary to avoid tearing the bark.
Make the first cut on the underside of the branch about 18 inches from the trunk.
Undercut one-third to one-half way through the branch.
Make the second cut an inch further out on the branch; cut until the branch breaks free.
Before making the final cut severing a branch from the main stem, identify the branch collar. The branch collar grows from the stem tissue around the base of the branch.
Make pruning cuts so that only branch tissue (wood on the branch side of the collar) is removed.
Be careful to prune just beyond the branch collar, but don't leave a stub. If the branch collar is left intact after pruning, the wound will seal more effectively and stem tissue probably will not decay.
The third cut may be made by cutting down and severing the branch. If, during removal, there is a possibility of tearing the bark on the branch underside, make an undercut first and then saw through the branch.
Research has shown wound dressing is not normally needed on pruning cuts. However, if wounds need to be covered to prevent insect transmission of certain diseases such as oak wilt, use latex rather than oil-based paint.
After the initial pruning at planting, hedges need to be pruned often.
Once the hedge reaches the desired height, prune new growth back whenever it grows another 6 to 8 inches.
Prune to within 2 inches of the last pruning.
Hedges may be pruned twice a year, in spring and again in mid-summer, to keep them dense and attractive.
Prune hedges so they're wider at the base than at the top, to allow all parts to receive sunlight and prevent legginess.
Renewal pruning for older or overgrown shrubs
Every year remove up to one-third of the oldest, thickest stems or trunks, taking them right down to the ground to encourage the growth of new stems from the roots.
Once there are no longer any thick, overgrown trunks left, switch to standard pruning as needed.
Rejuvenation pruning for older or overgrown shrubs.
Deciduous shrubs that have multiple stems (aka, cane-growth habit), and that have become very overgrown or neglected can be rejuvenated by cutting all canes back as close to the ground as possible in early spring.
That season's flowers may be sacrificed but the benefits from bringing the plants back to their normal size and shape outweigh this temporary "collateral damage."
This pruning technique works best for shrubs such as overgrown spireas, forsythia, cane-growth viburnums, honeysuckle and any other multiple stemmed shrubs that are otherwise healthy.
Within one growing season, these shrubs will look like new plantings, full and natural shaped.
With few exceptions, evergreens (conifers) require little pruning. Different types of evergreens should be pruned according to their varied growth habits.
Spruces, firs and Douglas-firs don't grow continuously, but can be pruned any time because they have lateral (side) buds that will sprout if the terminal (tip) buds are removed. It's probably best to prune them in late winter, before growth begins. Some spring pruning, however, is not harmful.
Pines only put on a single flush of tip growth each spring and then stop growing. Prune before these "candles" of new needles become mature. Pines do not have lateral buds, so removing terminal buds will take away new growing points for that branch. Eventually, this will leave dead stubs.
Pines seldom need pruning, but if you want to promote more dense growth, remove up to two-thirds of the length of newly expanded candles. Don't prune further back than the current year's growth.
Arborvitae, junipers, yews, and hemlocks grow continuously throughout the growing season. They can be pruned any time through the middle of summer. Even though these plants will tolerate heavy shearing, their natural form is usually most desirable, so prune only to correct growth defects.