Our mission is to share the wonders of the natural world by publishing books from experts in the fields of gardening, horticulture, and natural history. Grow with us.

Basic pruning techniques

by Timber Press on January 15, 2019

in Design, Gardening

Climbers are usually grown as one-dimensional plants—that is, they are trained up and across a surface. They are pruned for the same reasons as other plants, but they may also need to be coaxed into growing toward and onto their supporting structure.

To some extent you can determine the amount of basic pruning you will need to do by choosing good-quality plants that have no obvious signs of pests and diseases, damage, or injury and that are growing well (although that is not easy to tell during the dormant season).

When you are buying climbers, roses, and shrubs for your garden, select plants that have several healthy stems emerging from close to ground level. Trees with a vigorous single stem and sideshoots emerging at regular intervals almost at right angles to the main stem or trunk of the tree will form strong branches and a good framework as they mature.

Marking a Start
Before you prune any plant, it will help to have a basic idea of how that plant grows. You don’t need to be a botanist, but you should have an idea of the plant’s natural habit of growth—whether it should be erect, bushy, spreading, and so on—and when it flowers. This knowledge will give you some idea of the plant’s likely reaction when you prune it, although you should bear in mind that most plants will react differently to pruning at different times of the year.

A quick examination of the plant you want to prune will show that at the tip of each shoot there is a terminal (apical) bud, which is often called the growing point. Below this bud on the stem are arranged other smaller side buds, called lateral (axillary) buds. These are arranged in a particular way, which varies from plant to plant.

They get their name from the place where they form on the shoot—the leaf axil (or the angle where a leaf is attached to the stem of the plant). The position of these buds will determine where the future side (lateral) branches or flowering shoots are likely to develop.

The apical bud in the tip of the shoot influences the growth and development of the axillary buds by producing chemicals that discourage their growth, a characteristic known as apical dominance. If the apical bud is damaged or removed, its control is lost and the axillary buds or shoots respond by growing rapidly to form laterals or sideshoots. Apical dominance seems to be much stronger in younger plants and is often more significant when plants are undergoing some type of formative pruning.

It is useful to understand how a plant will respond when you have to decide just where to make a pruning cut. Don’t make the mistake of thinking that severe pruning is the best way to control vigorous growth in plants—in fact, severe pruning usually provokes the plant to grow even more vigorously.

As groundcover plants grow higher, they will leave gaps beneath. Stimulate new growth from the base by pruning the plants back every five or six years.

Positioning Pruning Cuts
On most of the plants you are likely to prune, the buds will be arranged along the stem at regular intervals in one of two ways: either alternately (one on one side of the stem, one farther up on the other side, and so on) or in opposite pairs (one on each side of the stem, directly opposite one another). The buds are usually closer together at the base of the stem and slightly wider apart as you progress upward.

If a plant has an alternate arrangement of buds, look from the tip of the stem downward and you may notice that the buds run in a spiral pattern down the stem. Where the buds are arranged in opposite pairs, look from the tip of the stem downward and you may notice that the pairs of buds are arranged roughly at right angles to one another. These bud (and leaf and stem) arrangements are designed to give each leaf the maximum amount of space and light.

On plants with the buds arranged alternately, any pruning cut should be at an angle, about 1–2in (2.5–5cm) above a bud, with the bud itself near the uppermost point of the cut. This is important because the healing of any cut is greatly influenced by the proximity of these growth buds. Usually, cuts are made to an outward-pointing bud to encourage an open structure of stems and branches. On plants with buds arranged in opposite pairs, any pruning cut should be about 1–2in (2.5–5cm) above a pair of buds, but at a right angle; this will leave a flat cut across the top of the shoot, so that both buds are left undamaged.

Despite the many types of trees available from plant nurseries, the most popular form for many gardens is still a standard tree, which has a clear, bare stem with no branches up to a height of about 6ft (2m) above soil level.

Timing
Pruning is often done in winter because it is convenient for the gardener rather than ideal for the plant. Pruning is a good way to keep warm in the garden when the weather is chilly and the ground is wet or frozen, making it impossible to dig or cultivate the soil. At times like this, we rely on other gardening tasks, such as pruning, to keep us busy until the soil conditions improve.

As a rule, most deciduous plants are best pruned either after they have finished flowering or in the fall, winter, and early spring when they are dormant. However, as with most rules, there are exceptions for practical reasons. Plants that are grown for their attractive fruit will be left unpruned for several years to get a good display of hips or berries. Some plants don’t respond well to pruning when they are dormant, especially in late winter or early spring, and pruning at the wrong time can kill a large section of the plant or, in extreme cases, the whole plant.

For this reason some plants, such as birch (Betula spp.), buckeye or horse chestnut (Aesculus spp.), maple (Acer spp.), poplar (Populus spp.), and walnut (Juglans spp.), are pruned in summer, when they are in full leaf, to protect them from bleeding copious quantities of sap. The leaves draw sap past the pruning wounds, keeping them relatively dry and reducing the chance of stems dying back.

Some plants are pruned at a particular time of year to protect them from specific pests or diseases. If fungal and bacterial plant diseases are common in your area, you will need to schedule pruning when the weather is dry. Dogwood anthrancnose and fire blight on crab apples (Malus spp.) can spread easily during wet spring weather.

Pruning and Training
With many pruning techniques, making a good clean cut at the correct place on the plant is only part of the story. Often pruning is carried out in conjunction with some form of training, which can take the form of tying growths into a particular position, or trimming away shoots that are trying to grow in a certain direction. The use of canes or stakes to guide a plant’s stems or shoots to grow in an upright position or the use of wires, trellis, and frames to steer growths in an angled or horizontal direction is usually practiced as the pruning is carried out.

It is important to remember that pruning cannot be carried out in isolation of other cultural practices when you are growing plants. Don’t neglect your plants’ nutritional needs, because removing large areas of leaf from growing plants (especially with summer pruning) can have a debilitating effect on them. Feeding, watering, and mulching are essential to maintain balanced, healthy growth and to help the plants to respond quickly after pruning is complete.

 

Steven Bradley spent over 20 years teaching horticulture at colleges around England and is now a freelance garden writer and broadcaster. He studied horticulture at Writtle, Cannington, and Pershore Colleges, achieving the RHS Master of Horticulture diploma. For more information, visit him at sungardening.co.uk.

 

 

Previous post:

Next post: