PRINCIPLES OF PRUNING

Why pruning is needed?

Proper pruning improves shrubs and trees in any number of important respects, but improper pruning can be more harmful than none at all. Skill in pruning is gained through experience, so do not shy away from the task. On the other hand, understand the basics before proceeding.

General pruning tips

Before you start out to prune, learn how plants grow. Trees and shrubs put on new growth each year from the ends of the branches (terminal buds) and from side branches (lateral buds). A plant’s direction and rate of growth are determined by its terminal buds.

Pruning tools
Ilustration, Lateral buds form branches and twigs that fill in the skeleton of major branches. Dormant buds, which are much less obvious and sometimes hidden below the bark, held in reserve. They only begin to grow if the plant suffers injury to its terminal and lateral buds. A key to skillful pruning is learning how to take advantage of lateral and dormant buds in redirecting growth or rejuvenating a plant.

The principal reasons for pruning are:

Pruning Methods

Under normal conditions, terminal buds grow faster than lateral ones by producing a chemical that retards the growth of lateral buds. Terminal-bud dominance varies according to the age and species of the plant. It is strong in most trees, especially young ones. It is relatively weak in shrubs, particularly those that are bushy.

Pruning methods
Illustration 2.2, If you cut away the terminal bud from a stem, the lateral buds below it will grow faster, and the stem will become more bushy.

Pruning Cuts

Pruning is the removal of older twigs and branches that have begun to harden and become woody. Unlike shearing, which is done during the growing season, pruning is usually done while the plant is dormant, that is, not actively growing.

Pruning cuts
Illustration 2.3, When making pruning cuts you are removing undesirable growth with an eye to encouraging beneficial future

The cardinal rule is to prune back to a branch or a bud, or you will leave a stub that will die back and cause decay and disease. Make pruning cuts no more than 1/4-inch above a bud or side branch.

Pruning cuts
llustration 2.4, Angle all pruning cuts at about 45 degrees, tilted in the direction the bud is pointing. A slanting cut leaves less stub and dries faster after a rain.
Buds localization
Illustration 2.5, Deciding which bud to cut back to is the key to successful pruning. Trees and shrubs have buds all along their branches, some pointing toward the center of the plant, others pointing out. Cut just above an outside bud. The resulting twig or limb will tend to grow outward and upward, for a healthy, attractive, spreading growth habit. If you cut to an inward, pointing bud, the limb may cross other branches and contribute to dense, tangled growth and a lack of air circulation and sunlight at the center of the plant.

Shearing

When you shear a hedge, you are removing all of its new terminal buds, thereby encouraging vigorous lateral growth for a dense, bushy hedge. At the same time you are keeping the hedge from growing too high. Shearing is usually restricted to removing soft, first-year growth that is easy to cut.

It is best to shear shortly after new growth begins in spring so that the lateral buds will have all season to grow and make the hedge bushy. If you make the common mistake of waiting until the end of the growing season, your hedge will not get bushy. You will also end up with unsightly brown tips, because no new growth will cover them.

Roses

Pruning the roses is not a mysterious art form. Roses are deciduous shrubs that flower on new stems, called canes, that grow from the base each year. As canes age, they lose vigor and produce fewer and fewer flowers. An old, neglected rose bush is an unsightly tangle of dead wood and old canes. To continue blooming profusely, rose bushes must be pruned once a year to stimulate the growth of new canes.

Pruning also lets light through to the “bud union” at the base of the plant. Most roses are bud-grafted, and the big, wood knob at the base is the graft. A rose produces more and healthier canes if its bud union gets plenty of sunlight in the late spring and early summer. Remember, though, that the bud union can be severely damaged by snow and frost. In colder regions, cover it with soil and mulch from first frost to last.

Most roses bloom in summer and should be pruned in March, just after buds begin to appear. In the Sunbelt regions, the best time to prune is in late January-February. In the Deep South, it is February. If you prune too early (December), you will stimulate premature growth that is vulnerable to frost damage. If you prune too late (April-May), you will waste energy the plant has put into early-spring budding and leafing. The ideal time is after the last killing frost, when buds halfway up the most vigorous shoot are beginning to swell, and buds near the tip have grown to about 1⁄4-inch.

Roses that bloom on the previous year’s wood should be pruned after they are finished blooming. A few roses bloom on both new and old wood. Prune each type of flowering wood as if it were a separate plant. Seal all large pruning cuts with tree paint or rose paste to prevent disease and speed healing. If you have a diseased rose plant, make sure to dip clippers in alcohol after pruning to prevent spread of the disease.

Pruning when Planting

If you buy a rose bush with a root ball wrapped in burlap or one grown in a container, the only pruning you need to do when planting is to cut back any dead, diseased, or damaged growth. If you buy bare root roses, prune away any broken or mangled root tips. Then remove all twiggy growth from the top of the plant.

Pruning when planting
llustration 10.1, Make sure to cut the canes back to within 6 to 12 inches of the base of the root union.

Maintenance Pruning

First, be sure to have on hand sharp pruning shears and a pair of stout garden gloves; most roses have very sharp thorns and are much easier to prune if you’re not constantly worried about being pricked.

Begin by removing dead, diseased, and damaged canes. Dead wood is brown and dry inside, even when it’s green outside.

Next prune away any crossing canes and lateral branches that may rub together. Disease and pests enter where bark is abraded. Remove crossing growth from the center of the plant to allow light into the bud union. A vase shape is the ideal skeleton for most rose bushes.

With young plants, that is all the pruning needed. On plants three or more years old, keep pruning. Cut away about one third of the oldest growth. Start by removing wood three or more years old. Then cut twoand- one year old wood back to the height you want to maintain.

To distinguish between new wood and old, look at the color of the canes. One-year-old wood is green with green thorns and vigorous green leaves. Two-year-old wood is brownish-green, and the thorns begin to look dull. Other wood is brown or gray or black.

Maintenance Pruning
Maintenance Pruning
Illustration 10.2, When pruning an old cane, cut it back to where young, green wood is showing. If a cane is brown or black from tip to toe, remove it at the bud union. Leave no stubs. Cut back to an outward-facing bud, and make the cut 1/4-inch above the bud and facing away from it.

For a balanced shrub, leave canes on the east and north sides of the plant 2 to 4 inches longer than those on the south and west sides. The latter will get more light and grow longer, catching up with the other canes by midsummer.

Remove suckers. Do not just cut them off above ground. Trace them back to their roots and pull them out. Check the number of buds at the nodes of the remaining canes. There should be only one bud at each node. If there are several, rub away all but one with your finger.
Maintenance Pruning
Illustration 10.3, When pruning an old cane, cut it back to where young, green wood is showing. If a cane is brown or black from tip to toe, remove it at the bud union. Leave no stubs. Cut back to an outward-facing bud, and make the cut 1/4-inch above the bud and facing away from it.

If you want your shrubs to produce a few large blossoms, prune more severely, removing more canes and cutting the remaining ones lower. If you want more, smaller blossoms, prune lightly.

Removing Flowers

During the flowering season, pruning is limited to removal of spent flower clusters. This prevents the shrub from producing hips (fruit and seeds) and encourages better blooming next season. Remove flowers by cutting back the stem bearing them to the first strong, outward, facing bud. These buds are located just above a leaf with five leaflets. Leaves with one, two, or three leaflets tend to have weak buds. Do not just nip off the flower. If you do, the weak growth just below the spent flower will produce weak, straggly growth.

Removing Flowers
llustration 10.4, Cut above the second 5-leaflet leaf from the top.

There are many different roses available, and there are minor differences in how each one should be pruned for the best effect and the healthiest plant.

Hybrid teas and hybrid perpetuals. These, the most popular of all roses, should be pruned annually to keep them blooming well. The more vigorous varieties like ‘Peace’ should, however, be pruned lightly or they will produce lots of leaves and few flowers.

Floribundas. Generally, moderate pruning is in order, but the best method is to prune some growth lightly, other growth severely. This produces both an earlier and a longer display of blossoms.

Miniatures. It is best not to prune miniature roses back too much when you plant them. If they send up strong shoots that make their shape unbalanced, remove these shoots at their point of origin.

Polyanthas. These roses tend to be twiggy and produce much dead wood. Be sure to keep their centers open.

Climbing hybrid teas and floribundas. Little pruning is required. Simply remove dead or worn-out canes and stems that have flowered.

Ramblers. They blossom best from short laterals sprouting from long, unbranched canes produced the previous year. You can distinguish a true rambler from other climbing roses by the many new shoots that sprout from the base while the plant is in full bloom. Never cut these away. They are the canes that will bloom next year. Prune ramblers in August, cutting the old canes that have flowered to the base.

Pillar roses. Unlike most climbing roses, pillars grow and flower upright. (Most climbers only flower well when trained horizontally.) In Autumn, remove worn-out canes whose bark has grown rough and dark and whose laterals are producing weak, twiggy growth. Also cut back one or two of the new canes by about two thirds of their length. In summer remove spent flowers.

Species and shrub roses. They require little pruning, but “little” does not mean none. During the winter tip back all vigorous canes and laterals to encourage abundant flowering. If the bush becomes overcrowded, remove one or two of the oldest canes. Regularly remove spent flowers.

Rose hedges. Floribundas are usually used in rose hedges, which can be pruned as you would any hedge. Do not cut back more than one third of the hedge.

Standards. These, usually formed from hybrid tea or grandiflora roses, can be pruned back by about half to keep the head compact. Remove any shoots growing from the trunk below the head.

Shade Trees

A tree’s first few years are critical. Pruning then has a profound effect on the ultimate size, shape, and health of the mature tree.

Pruning when Planting

When planting a young tree, prune to achieve balance between the roots and the stem. Shade trees are usually sold balled and burlapped, that is, with most of their roots intact and surrounded by soil. Such trees need little pruning when planted. Simply remove any twiggy growth that won’t be part of the tree’s framework of branches. Container-grown trees need almost no pruning, since none of their roots have been removed. Prune only to remove dead or broken branches. Plants that have been too long in the container can form circling roots. Prune them; if left, they could become girdling roots.

Bare-root trees (in which many of the roots have been removed or damaged),may require some pruning when planted, but the old practice of removing up to one third of the stem and half of each branch has been seriously questioned. Instead, prune any broken branches or roots before planting.

Pruning when Planting
Illustration 4.1, Prune young shade trees to establish branch patterns that preserve the natural habit of the tree. Certain trees – pin-oaks, birches, poplars, and the like – form a single central trunk with clearly subsidiary side branches. Any tendency of such trees to produce more than one leader calls for removal of the weaker ones.

Ornamental Trees

Like shade trees, ornamental deciduous trees grow on a framework of older branches and need only infrequent maintenance pruning. Follow the same rules for pruning at planting time.

Ornamental Trees
Illustration 5.1, In the first year, while the plant is dormant, remove weak or un- ruly shoots, crossing branches, and suckers
Ornamental Trees
Illustration 5.2, In the spring of the second or third year, remove poorly spaced branches. Thereafter, leave the plant alone, pruning only for dead, dis- eased, or damaged wood or to correct a poor shape.
Ornamental Trees
Illustration 5.3, Train flowering trees as trees rather than large shrubs; with a central leader. Cut off all suckers that sprout from their roots.

The best time to prune most flowering trees is just after the blossoms fade unless you want to leave attractive berries, on which case prune in late winter.

Ornamental Shrubs

Most deciduous flowering shrubs require little more than regular maintenance pruning: removal of dead, diseased, or damaged branches whenever you notice them. Remember, a plant should not be pruned unless there is a good reason for doing so. Some shrubs may need to be cut back to keep them from getting too tall or too broad. Because they renew themselves by growing new stems from the roots or from the base, they do not require pruning to encourage a balanced, open structure of large branches as do trees.

Some shrubs, benefit from occasional drastic pruning. Cut back almost to the ground, these plants will virtually replace themselves with new growth. Others, however, are better served by less drastic renovation pruning spread over two or three seasons.

Before pruning a flowering shrub, check to see whether it flowers on wood produced the same year or on year-old wood that grew during the previous season. While there is no foolproof way to tell if plants bloom on old or new wood, most plants that bloom before the first of June do so on old wood, and those that flower later, bloom on new wood.

If flowers form on old wood, the shrub should be pruned immediately after the flowers fade. If you prune these plants in winter or spring, you will cut away flower buds. If you do not prune them immediately after they flower, they won’t have enough time to develop a new set of buds to flower the following spring.

If flowers are produced on new wood, the shrub may be pruned in late winter or early spring before the buds become green.

Shrubs that flower on old wood should be pruned in the following manner. To remove dead, diseased, or damaged wood, follow these steps:

Cut back shoots that have borne flowers, leaving vigorous young shoots lower down on the main stems.

Remove any puny or overly vigorous shoots and suckers that spoil the shape of the plant.

On shrubs three or more years old, begin to remove some of the oldest shoots at the base as close to the ground as possible, to simulate the growth of new shoots. Remove one out of every three to five older shoots depending on the size of the shrub.

Shrubs that flower on new wood should be allowed to form a strong framework of branches in their first several years. In the first year, tip back shoots to the first strong bud or pair of buds. Remove puny, overly vigorous shoots.

In the second year and thereafter prune back new shoots to within one or two buds of last year’s growth. In the fourth or fifth year begin to remove older branches at the base.

Renovation

When restoring old shrubs, follow these guidelines, remembering to prune according to the plant’s natural form. Remove dead, damaged, diseased, weak or badly placed stems. If a shrub has become too large, cut several of the oldest stems to the ground and cut the remaining ones to just below the height you want for the shrub. Within a year or two the branches will grow back and hide the pruning wounds. In the future, prune annually to maintain desired height and breadth.

If a low-growing shrub has become too dense, prune half the stems to the ground the first year. Prune the remaining half the second year. If the shrub is very vigorous, cut all the stems to the ground the first year.

If a shrub’s growth has become thin and floppy, cut back all the leggy stems by half and remove some of the oldest stems to the ground.

If a shrub has become too twiggy, with many small branches at the ends of the branches, prune the oldest branches to the ground and cut off the outer twiggy growth.

In all of the above instances a healthy and reasonably vigorous plant will come back with lush growth and fill out within three years.

Ornamental Vines

Whether they climb, creep, cling, twine, or flop and scramble, vines have one thing in common: given favorable conditions they grow like crazy. Pruning vines is largely a matter of keeping them in bounds, and that is best done by controlling growth from the day you plant a vine.

When planting, select several of the strongest shoots and prune them back to half their length to encourage more new shoots to grow from the base.

As a vine grows, keep it in check. If you want it to be compact, continually prune terminal growth during the growing season. If you want it to ramble, cut to the base all but three or four of the strongest shoots. Be sure to prune to let light reach the base of the vine or it will become bushy on top and bare below.

Most flowering vines bloom on wood formed the previous year, so try to avoid drastic pruning in early spring or you will remove the flower buds. On the other hand, all drastic pruning of vines should be done when the plants are dormant.

Ornamental Vines
Illustration 9.1, When planting a vine, prune about half the strongest shoots to half their original length. This will encourage growth at the bottom of the vine as well as above.

Broadleafed Evergreens

Broadleafed evergreens need very little pruning; many are better left alone. Pruning is beneficial and similar for all such plants.

Maintenance pruning is simple. Prune dead, diseased, or damaged wood anytime. Remove faded flowers immediately after they are spent for the best flowering the following year. At the same time prune back branches that are too long.

To maintain a compact shrub, periodically snip off the terminal buds of new growth during early summer to induce the growth of lateral and latent buds. Be careful to cut off only the smaller terminal buds and not the fatter blossom buds that are next year’s flowers.

In time, broad leafed evergreens become leggy and need rejuvenating. In the South, cut the plant back to within about a foot of the ground. In colder areas, spread this drastic pruning over several years, removing a third of the stems annually. Renew plants in late winter or early spring.

Larger broad leafed evergreens require little beyond removal of dead or damaged limbs and suckers. Large wounds are very slow to heal; avoid making them if possible.

Broadleafed Evergreens
Illustration 7.1, To stimulate branching, remove the he ad just above the light-colored new growth of the current season.

Hedges

Creating a hedge requires the regular shearing of vigorous plants to produce dense, contained growth. You cannot shear a formal hedge too often to keep it looking its best. Informal hedges may need shearing only once or twice a year.

Begin shearing a new hedge in its second or third year. Shear it regularly thereafter. Do not allow a hedge to reach its desired height and then begin shearing it for a compact, dense habit. Develop a small, dense hedge first then let it slowly reach the desired height.

Always prune an hedge so that it is tapered toward the top. This allows sunlight to reach all the foliage, even at the base. If you sheared the sides of a hedge perpendicular to the ground, or worse, slanting out toward the top, lower foliage will succumb to the resulting shade, and the hedge will become a top-heavy eyesore.

Hedges
Illustration 8.1, When shearing to shape a hedge, start at the bottom and work up. Keep your shears pointed slightly inward to achieve the desired taper. In the north, do not make a flat-topped hedge; it will carry more snow and ice and will break under the weight.

Provided they are vigorous and healthy, most overgrown hedges (andespecially deciduous ones) respond very well to drastic pruning. Cut them back to a foot or more from the ground, and within a new year they will be good as new. Some evergreen hedges can be similarly renewed, but be sure branches have some leaves remaining. Evergreen hedges are yew, boxwood, and holly.

The best time to shear a hedge is when it is making its fastest growth. For needle evergreens that means early summer. Since they put on all their growth over a short period, they will not require periodic shearing after midsummer. Deciduous plants like privet and barberry require periodic shearing throughout the summer. Shear broadleafed evergreen hedges throughout the year. Shear flowering hedges only after the blossoms have faded.

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