Pruning is one of the most important tasks for any gardener. It helps to encourage plants to continue growing healthily and attractively. But pruning is also regarded as a chore by many, resulting in hasty or improper pruning. This can be more dangerous to a plant than any type of pest or weather damage. This article will explain the ins and outs of pruning, such as when to do it, what tools to use, and how to avoid incorrect pruning.

What is pruning?

Pruning is the act of removing dead branches and damaged or diseased stems to help plants redirect their energy for more efficient growth. In nature, pruning happens very slowly – old branches gradually die before being jettisoned during strong winds or through animal activity. Gardeners often use pruning to eliminate spent growth from previous seasons, helping to stimulate the plant’s next growing cycle. Pruning is also used to train plants into aesthetically pleasing shapes or to prevent them from growing too large for the space they’re planted in. But if pruning is performed incorrectly, it can do more harm than good. Poor pruning can result in stunted growth, an ugly appearance, or weakened branches. The correct way to prune often depends on the specific needs and characteristics of each particular plant.

Types of pruning

Gardeners use several different pruning techniques to achieve different results. The two basic pruning methods are heading and thinning.

Heading

Heading involves cutting off a section of the plant near the tips of the limbs or branches. Deadheading is the most common type of heading and is used to remove wilting flowers on shrubs during the growing season to help the plant redirect energy to fresh shoots, keeping the plant in bloom for longer.

Thinning

Thinning is a more aggressive pruning method that sees the gardener remove entire limbs or branches back to where they naturally branch off from the main stem of the plant, leaving some young buds behind. This helps to preserve the natural appearance and growing habits of the plant. Thinning is often used to even a plant out and allow inner branches to receive more sunlight.

When to prune

The best time to prune depends on the type of plant and the desired results. Pruning tasks can be performed across the whole year, but it’s always best to follow the natural growth processes of a plant. For example, flowering shrubs should be pruned once the flowering season has ceased. This helps to prepare the shrub correctly for the next growing season. Several types of plants also become dormant in winter to conserve energy during the colder months. Heavier pruning at this time puts the plant in the best position for excellent growth next year. Research each plant to determine the best time of year for pruning.

Tools for pruning

Here is a brief description of some basic tools that can perform the majority of pruning techniques:

Hand clippers/shears

The most common pruning tool is a good-quality pair of hand clippers. These can be anvil clippers or scissor-action clippers. Anvil clippers have two broad, thick blades while scissor-action clippers have curved blades – the quintessential secateurs. Hand shears will handle most small, thin stems during pruning.

Lopping shears

For tougher or thicker stems, a pair of lopping shears are the best tool. These consist of a clipping blade attached to two long handles. Loppers can handle stems thicker than half an inch in diameter. A vice-like movement is used to operate these shears, using both hands.

Pruning saws

For very thick stems or branches, pruning saws can be employed. These can resemble a somewhat triangular bow or they can be folding. Pruning saws have wider-spaced teeth than standard carpentry saw and cut on the pull, which is easier when dealing with live wood. All of these tools must be sharpened regularly to maintain their effectiveness. Cutting tools must also be disinfected after being used to remove diseased branches. This stops healthy branches from being contaminated.

Healing response to pruning

As beneficial as pruning is, it also creates a window of vulnerability for the plant. Right after pruning, plants may be susceptible to pests and diseases through wounds on the freshly cut stems. Of course, plants naturally recover from this, but it takes time. Once a stem is trimmed, the wound will effectively scab over to create a callous. This helps to seal the plant against potential problems. While some gardeners may suggest treating wounds with things like pruning paint, it’s better to let the plant heal itself naturally.

Pruning young trees

The first thing to do when pruning young trees is to trim away any stems or thin branches that might be crossing over each other or that might be carrying disease. Pruning away too many branches can result in stunted growth, as the plant has fewer available leaves to draw in energy and continue its growth naturally. Trees need plenty of space between their support branches to promote natural growth and should be pruned with this in mind. The central trunk should ideally be left in place. When removing smaller branches, always cut the branch close to, but not beyond, the spot where they join the main trunk. Always cut at a similar angle to how the branch was originally growing. Young trees can be gradually trained to have their lowest branches reach the desired height. For example, a tree growing over an outdoor seating area needs to offer enough headroom underneath its lowest branches. Pruning away too many low, small branches too quickly results in a weak trunk. Once a low branch is thicker than an inch, it can be pruned correctly.

Pruning mature trees

When it comes to mature trees, most gardeners are better off leaving any heavy maintenance to professional arborists. Trying to cut mature, developed branches is difficult and dangerous. But gardeners can maintain a healthy mature tree by tackling smaller, lower branches. Mature trees do not generally need too much pruning maintenance and only really need to be trimmed to keep them at a certain size or to prevent disease from spreading. For most types of trees, the best time to prune is in winter once the tree has become dormant.

What not to do when pruning

Unnecessarily drastic pruning is one of the worst pruning practices. This is especially harmful to bushes and shrubs. Some gardeners will use “topping” – a form of heading that involves shearing off most of the top of the shrub – to reduce size. However, this only stimulates growth right at the top of the shrub. The branches lower down do not benefit, leaving them bare and ruining the look of the plant. Another detrimental pruning practice is called “bench cutting”. This entails pruning the main vertical stem of a tree or shrub horizontally, making the cut above a secondary branch that is growing laterally. This causes the plant to focus on growing laterally, rather than vertically and can ruin the spacing of the foliage. Instead, stems or branches should be cut close to the main trunk at a similar angle to where they had already been growing. This maintains a more natural shape and spacing for the plant.