Pruning Demystified

This is an excerpt from the Book called “The Homeowner’s Complete Tree & Shrub Handbook” by Penelope O’sullivan . Continue reading to learn more about Pruning Demystified, thanks to the author.

Until you understand its simple logic, pruning can be one of gardening’s great mysteries. Pruning plants for the right reasons with the right tools at the right time and in the right places on the plant can make both your plants and the landscape that surrounds them more refined and more beautiful. There are many reasons to prune, and all of them make good sense.

Healthier, more vital plants. Cut off dead or diseased branches not only to improve a plant’s appearance, but also to prevent the spread disease. Remove crossed and rubbing branches, a condition that can wear away protective bark, compromising the plant’s health. Prune back limbs damaged by ice, heavy wet snow, strong winds, or mechanical damage. In some cases, you may have to remove whole plants, while in others only damaged areas need cutting.

Beauty. Good pruning can show off or even improve the basic form or structure of the plant.

Safety. If a low branch extends over a path, you may need to remove it to prevent tripping. Phone the power company if high limbs interfere with power lines. Prune back bushy plants growing near a road or at corners where the plants may block a driver’s line of vision on the road or emerging from a driveway.

Tender-Loving Tool Care

Whatever tools you choose, keep them clean, since dirty blades can spread pests and infections from plant to plant. Disinfect cutting surfaces with rubbing alcohol applied to a clean rag or paper towel. Tuck a fresh rag in your belt for wiping dirt and sap from the blades before each cut.

When necessary, follow the manufacturer’s directions for taking apart pruners and saws. Remove rust from blades with fine sandpaper or a wire brush. Oil joints and springs regularly, and use a sharpening stone to hone the outer beveled edge of dull blades. Taking good care of saws and pruners ensures clean healthy cuts that benefit rather than damage the tree.

Pruning Tools That Are A Cut Above

Hand Pruners. Use hand pruners for stems up to ½-inch wide that are easy to reach. You’ll find two kinds of hand pruners, each of which has specific uses. Bypass pruners (A) have two blades and cut like scissors. The upper blade curves past the lower blade, making it easy to cut cleanly into live green wood. Anvil pruners (B) on the other hand, make rough cuts with a knifelike action. They are best for thinning brush and removing hard or dead wood because their upper cutting edge squeezes the stem against an anvil or metal cutting block. Keep your cutting blade sharp, because a dull cutting edge can mash the stem. If you want one pair of hand pruners, then splurge on the best bypass pruners that you can afford. They give you more flexibility and do less damage to live wood. Some companies make hand pruners for lefties like me.

Loppers. Similar to hand pruners in the way they work, loppers (C) usually have longer handles and blades that let you cut branches up to 2 inches across. They come with either bypass or anvil-style blades. Loppers are good for reaching deep into a shrub and thinning excess growth, for cutting thorny branches, and for more forceful cuts because of the extra leverage the long handles provide.

Pruning Saw. A folding pruning (D) saw is another useful item. I use my saw, which has a blade about 6 ½ inches long, to make clean cuts in stems less than 4 inches across. The pullback action required for cutting makes pruning the fat stems of my dieback paulownia fast and easy each fall.

Pruning A Branch

Dr. Alex Shigo, former chief scientist in the U.S Forest Service, discusses natural target pruning in his book Modern Arboriculture. He recommends that proper pruning cuts be made close to the branch collar (the bulge under a branch where branch and stem tissues intersect) not flush with the trunk. Unlike humans, who heal by renewing injured tissue, trees compartmentalize, or close off, an injury from the rest of the tree by forming new wood over the damaged spot. Flush cuts that take off the branch collar enlarge the wound and spread more decay within the tree.

Let pruning wounds heal naturally. Don’t paint them with wound dressing; dressings slow the healing process and keep the healthy new wood from forming.

Trees look their best when natural growth patterns guide your pruning efforts. Don’t top trees. Topping is the practice of cutting back, or “heading,” a tree’s large branches, leaving long, ugly stubs from which many weak sprouts will grow. Topping destroys a tree’s looks and makes it prone to disease and decay. It’s better to remove a too-big tree, replacing it with one that suits the site, than to take this drastic and mistaken measure to control tree growth.

The drawings below (The Three-Part Cut) illustrate the technique for pruning off any branches that are at least 1 ½ inches in diameter.

The Three-Part Cut

Make a short cut under the branch away from the branch collar, then make a second cut above and farther out on the branch.
Remove the bulk of the limb.
Remove the rest of the limb by cutting the branch off at the collar from top to bottom. The collar’s size and shape affect the cutting angle for each particular branch. Don’t leave a stub on the collar, but avoid cutting branches flush with the trunk.

Timing Your Pruning

Among the factors that determine the best time to prune woodies are why you’re growing them and when they bloom. Did you plant them for lush leaves, lavish flowers, or luscious fruits? Do they bloom in winter, spring, summer, or fall? And when do they form flower buds on their branches?

Basic Pruning Guidelines. Pruning deciduous trees and shrubs during late fall and winter dormancy helps limit contact with insects or fungi, which tend to be more active in warm weather. Dormant-pruning plants in the rose family helps prevent fireblight but many affect that year’s flowers. Pruning when the trees are bare also you to see the shape of the tree.

Flowering Trees And Shrubs. The general rule is to prune flowering shrubs and trees that bloom on new wood (the current growth) in late winter or early spring before the start of this season’s growth. Prune those that bloom on old wood (stems developed before the current growing season) soon after flowering to avoid removing this year’s blossoms.

Problematic Branches. You can remove dead, damaged, or diseased branches any time. It’s best to remove crossed or rubbing branches when dormant, especially if they ruin the plant’s structural appeal by making it look congested. Many shrubs need little pruning beyond that.

If you’re busy, you may not have much choice about when to prune: you may not have much choice about when to prune: you just prune when you have free time. That’s okay even for flowering trees and shrubs, if you don’t mind sacrificing one season’s flowers. By selectively pruning shrubs blooming on old wood soon before they bloom, you’ll give up some flowers. But if, for example, you clip a lilac hedge in late summer after it has set buds for the following spring you may be cutting off all the flowers.

Flowering Plants To Prune After Blooming

Prune plants that bloom on old wood as soon as possible after flowering, preferably within a month.

White forysythia Abeliophyllum distichum

Serviceberry Amelanchier species

Chokeberry Aronia species

Alternate-leaf butterfly bush Buddleja alternifolia

Sweetshrub Calycanthus species

Camellia Camellia japonica

Redbud Cercis species

Flowering quince Chaenomeles speciosa

Fringetree Chionanthus virginicus

Flowering dogwood Cornus florida

Kousa dogwood Cornus kousa

Cornelian cherry Cornus mas

Winter hazel Corylopsis pauciflora

Daphne Daphne species

Deutzia Deutzia gracilis

Pearl bush Exochorda x macrantha

Forsythia Forysthia hybrids

Gardenia Gardenia jasminoides

Witch-hazel Hamamelis species

Big-leaf hydrangea Hydrangea macrophylla

Oak-leaf hydrangea Hydrangea quercifolia

Japanese kerria Kerria japonica

Beautybush Kolkwitzia amabilis

Magnolia Magnolia species

Apple, Crabapple Malus species

Sweet mockorange Philadelphus coronarius

Almond, apricot, cherry, peach, plum Prunus species

Ornamental pear Pyrus calleryana

Azalea and rhododendron Rhododendron species

Flowering currant Ribes sanguineum

Rose (once bloomers) Rosa species

Bridalwreath spiraea Spiraea prunifolia

Thungberg spirea Spiraea thunbergii

Japanese tree lilac Syringa reticulata

Common lilac Syringa vulgaris

Korean spice viburnum Viburnum carlesii

European cranberry bush Viburnum opulus

Double viburnum Viburnum plicatum f.tomentosum

Weigela Weigla florida

Flowering Plants To Prune When Dormant

Prune shrubs and trees that flower on the current season’s growth (new wood) in late winter or early spring before they start growing and before bloom. Depending upon how large you want the shrub to grow, you can cut them back as far as the first pair of buds above the soil. For taller shrubs, prune plants higher above the ground.

Glossy abelia Abelia x grandiflora

Groundsel bush Baccharis halimifolia

Barberry (deciduous) Berberis species

Butterfly bush Buddleja davidii

Beautyberry Callicarpa species

Sasanqua camellia Camellia sasanqua

Blue mist Caryopteris x clandonensis

Summersweet Clethra alnifolia

Smokebush Cotinus coggygria

Rose of Sharon Hibiscus syriacus

Smooth hydrangea Hydrangea arborescens

Panicle hydrangea Hydrangea paniculata

Golden raintree Koelreuteria paniculata

Crape myrtle Lagerstoemia indica

Bush clover Lespedeza thunbergii

Heavenly bamboo Nandina domestica

Sourwood Oxydendrum arboreum

Hybrid tea Rosa cultivars

Elderberry Sambuscus species

Japanese spirea Spiraea japonica

Snowberry Symphoricarpos species

Blackhaw Viburnum prunifolium

American cranberry bush Viburnum trilobum

Chaste tree Vitex agnus-castus

‘When grown for foliage

Pruning Broad-Leaf Evergreens

In general, broad-leaf evergreens need little pruning. When necessary, prune them just before spring growth begins or immediately after flowering. If you choose the former, you’ll give up some blooms this year, but you’ll take advantage of their spring growth spurt for rejuvenation. Cut off dead, sick, injured, crossing, or rubbing stems, as well as stray stems for better shaping. Some broadleaf evergreens may need more extreme pruning, particularly if you’ve put shrubs like jumbo rosebay rhododendrons (Rhododendron maximum) in foundation plantings without taking account of their mature size.

Deadheading Rhododendrons

Deadhead faded flowers of broad-leaf evergreens, such as rhododendrons, andromeda, and mountain laurel, just as you would the deciduous common lilac. Detaching faded flowers before seeds develop encourages these shrubs to direct their energy into next year’s buds. As a result, plants look neater and will flower more next year. To deadhead rhodos, grasp a branch in one hand and a flower truss or cluster in the other, then carefully snap it off at its base with a quick twist of the wrist.

Pruning Deciduous Trees

Some deciduous trees produce excessive sap in late winter and early spring, just before and when new growth begins. If you prune these trees, known as bleeders, during that time, sap runs from the fresh wounds. Because we love our trees, we project our feelings onto them and assume that “bleeding” hurts. It doesn’t. Nor does it injure the tree. Prune the following bleeders during dormancy. If flowing sap bothers you and you don’t like pruning in late winter or early spring, make cuts after the leaves have unfurled, around July. Do not prune when the tree just starts leafing out, however, or from late summer to mid-fall, when new weak growth can occur and the presence of pests and diseases is high.

Deciduous Trees To Prune When Dormant

Maple Acer species

Horse chestnut Aesculus hippocastanum

Birch Betula species

Hornbeam Carpinus species

Hickory/pecan Carya species

Yellowwood Cladrastis kentukea

Beech Fagus species

Walnut Juglans species

Osage orange Maclura pomifera

Mulberry Morus species

Poplar Populus (some species)

Oak Quercus species

Willow Salix species

Chinese scholar tree Sophora japonica

Linden Tilia species

Elm Ulmus species