Regional Gardening Reports :: National Gardening Association

In the Garden:
Middle South
February, 2008
Regional Report

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This tree is an example of espalier; the tree has been pruned to a two-dimensional shape to lie flat against a wall.

It's Time to Prune

Late winter is the time to prune most woody landscape plants. Pruning during the dormant season allows you to better see branch structure and encourages a flush of vigorous new growth in spring. By waiting until the coldest winter weather has passed, you minimize damage to tissue around pruning cuts.

The exceptions to the late-winter pruning are spring-flowering shrubs, including azaleas, rhododendrons, forsythia, and weigela. These plants bloom on old wood -- the flower buds are formed the previous summer. Prune these now and you'll prune away potential flowers; instead, prune just after bloom.

Trees and shrubs that bloom in summer, including butterfly bush, rose of Sharon, beautyberry, and crape myrtle, produce flowers on new wood -- the flower buds form in spring and early summer on new growth. Prune these now to encourage new growth with abundant flower buds.

Every pruning cut should have a purpose. Research each type of plant to determine its natural growth habit and optimum pruning time and technique. Some plants thrive with repeated shearing; others don't. If a tree or shrub is grossly out of proportion where it stands in your landscape, consider removing it and planting something more appropriate. Repeatedly hacking back overgrown plants is often detrimental to the plant and results in an unnatural, awkward form.

There are three main reasons for pruning. Keep these in mind, in this order:

Prune for safety. Remove branches that obscure visibility or that are hazardous to pedestrians and people mowing. Remove weak and overhanging branches that could fall in a storm. Have your local utility or a professional arborist prune trees near utility lines.

Prune for health. Prune damaged and diseased branches, and those that are rubbing against each other. Remove weak growth to promote increased vigor in remaining branches. Prune crowded growth to improve air circulation.

Prune for aesthetics. Prune to maintain desired size and shape, to improve flowering or fruiting, to increase light penetration, and to improve the overall appeal of your landscape.

Pruning terminology can be confusing. As you consult a reference for each of your plants, keep the following glossary handy.

Types of Plants
Broad-leaved evergreen: an evergreen plant with broad leaves rather than needles. Examples: rhododendron, azalea, mountain laurel, and boxwood.

Narrow-leaved evergreen: an evergreen plant with needle-like leaves. Examples: pine, spruce.

Deciduous: describes plants that produce leaves during the growing season, then drop their leaves during the dormant season. Examples: maple, poplar.

Plant Parts: Branches
Branch axil: the angle formed where a branch joins another branch or trunk. Also known as a crotch.

Branch angle: the angle between two connecting branches. In general, branches with angles (less than 60 degrees) are weaker than those with wider angles.

Included bark: the bark enclosed in the branch axil between a branch and a trunk; the more bark included in a branch angle the weaker the joint. Narrow branch angles usually result in more included bark.

Branch collar: a ring of tissue that forms around the base of a branch; appears as a bulge where the branch connects to the trunk.

Lateral branch: a branch originating from the main trunk.

Lateral bud: a bud on the side of a branch.

Scaffold: a branch left unpruned so it will become a part of the framework of the tree.

Terminal: the end of a branch.

Terminal bud: the bud at the end of a branch.

Candle: early spring growth of evergreen shoots before the needles expand and stiffen.

Canopy: the branches and leafy parts of a tree; also known as the crown.

Plant Parts: Trunks
Leader: the primary vertical growth.

Central leader: the main trunk of a tree from which other branches develop. Trees with a strong central leader and pyramidal shape, such as most conifers, are called excurrent. Those with many lateral branches and a roughly spherical canopy, such as most deciduous trees, are called decurrent.

Multiple leaders: two or more branches growing strongly vertical.

Competing leaders: two or more branches competing for the strongest central growth of the tree. Usually one should be removed.

Multiple-stemmed plants: plants that tend to grow with multiple stems or trunks.

Caliper: describes the diameter of the trunk of a tree, usually measured six to 12 inches above ground.

Other Terms
Cambium: a layer of tissue underneath the bark where cell division and growth takes place.

Dieback: death of stems and branches; usually due to adverse weather conditions, insects, or disease.

Dormant: the time of the year when a plant is not growing.

Drip line: the outer boundary of the canopy.

Sucker: a shoot that sprouts from the base of a tree.

Water sprout: a vigorous vertical shoot that arises from a mature branch.

Types of Pruning

Crown raising: removing lower branches to provide clearance, such as for pedestrians or vehicles.

Crown reduction: removing branches to reduce the height of a tree.

Crown thinning: removing interior branches to increase light penetration and air movement through the crown of a tree.

Coppicing: cutting back a shrub nearly to the base, resulting in a flush of new growth. Not all shrubs respond well to this technique; shrubs that do include butterfly bush, caryopteris, and red-twig dogwood.

Espalier: training a tree on a wire or trellis against a wall.

Heading back: pruning shoots back to a lateral branch or bud.

Pollarding: pruning all new growth back to the same spot on the branches each year, leaving swollen stubs that sprout flushes of vigorous shoots. Some plants adapt to pollarding, but many, especially large trees, are weakened by the practice. Must be done every year or two.

Shearing: repeatedly cutting all branches of a shrub or hedge back to the same length to create a uniform, manicured shape. Can be stressful to plant, and not all shrubs respond well to shearing.

Topiary: pruning and/or training a plant into a specific shape, often geometric.

Topping: Cutting back large limbs of the entire canopy to drastically reduce the size of a tree. Very stressful and can result in the death of the tree.

Training: Using pruning, tying, staking, and other means to direct growth of a plant.

Vertical branch spacing: distribution of branches up and down the trunk of a tree.

Wound: area where the bark of a plant is cut or damaged.

Wound dressing: specially formulated material applied to pruning cuts. Generally not needed except on trees susceptible to diseases such as Dutch elm disease and oak wilt. Also called pruning paint.

Pruning Tools
Anvil pruner: hand tool with a straight blade that strikes a flat surface.

Bypass pruner: hand tool with curved blades that slide by each other.

Lopper: cutting tool with long handles that provides more leverage for branches too large for hand pruners.

Pole pruner: a long-handled pruner for reaching into the canopy.

Pruning saw: cutting tool with large teeth designed for live trees; often folds for transport.

Pole saw: long-handled tool with a pruning saw on the end for pruning large branches in the canopy.

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