
Why, What and When to prune
Like feeding your plants, pruning is one of the essential practises in gardening. It plays a vital role in supporting healthy plants. In this feature, we talk about why, what and when to prune.




By removing certain parts of a plant – buds, branches or roots – you can promote healthier growth, stimulate new growth, and improve the shape. You can also control to some degree the spread of pests and diseases to name just a few. Here are some of the benefits of pruning:
Rejuvenate
One of the most important reasons to prune, is to stimulate new growth, sometimes bushier growth. This in turn produces more stems and more leaves and ultimately more flowers. Over time, plants will become leggy and lose their vigour. There are various degrees of pruning. From a simple pinching with your fingers, to more extreme pruning to rejuvenate and enhance.
Finger pruning or pinching
The lightest of pruning is to pinch off the new shoots at a node. This forces the plants to make two or three new stems. The reason to do this is to create bushier plants – more leaves in herbs for example. Finger pruning is also done on Hybrid Tea roses to stagger and extend the flowering flush. Not all roses though need this treatment. It also encourages the roots to absorb nutrients for growth and flowers and encourages new basal shoots which give the plant its shape for the new season. This is also applicable to young seedlings or bedding plants. Specifically those which tend to want to reach for the skies rather than filling out and bushing out first. Examples of this are snapdragons – the tall growing varieties, sweet peas, delphiniums and tall flowering zinnias.
Deadheading
The pruning process whereby flowers and seed heads are pruned or removed to encourage new flowers to bloom and to keep the plants looking neat. However, on some plants like self-seeding perennials, it’s important to leave the flowers to form seeds that can then be dispersed to continue the cycle. Seed heads also provide food for birds in winter. When it comes to herbs and some veggies like lettuce, you can prolong its leafy growth by pinching out the flowers as soon as they appear and getting more edible green out of a plant.
Light and medium pruning
This is for general maintenance of plants that are spaced far apart or perhaps getting too much shade. For woody plants this leaves 4 – 5cm new wood growth and neatens up the plants.
Severe pruning
This is mainly for plants such as roses, hardwood- and semi-hardwood shrubs (Mackaya bella, camellias, hibiscus, euonymus, salvias, gauras, and penstemon) that have become bare, with little leaf growth on the lower third or two thirds of the plants; or plants that are planted close together and that grew tall the previous season, to help encourage bushier growth going into the new season. This type of pruning involves cutting back to 40cm from the ground. Woody plants like lavender and rosemary should never be cut back in this fashion. There should always be some leaf cover left on the plants to keep the plants going while the new growth appears.
READ MORE: Check out this month-by-month pruning guide
Improve fruit flavour
By removing branches that are crossing or congesting within the tree framework, better quality and sized fruit is also produced, ending up with better flavour.
Stimulate flower and fruit production
An important task in fruit trees is to increase yields. To do this, the plant needs the maximum amount of light they can get for flower production which in turn forms the fruit. A shape of the tree will determine how the sunlight gets to the middle of the tree for maximum flower budding and ultimate fruit formation.
Reduce transplant shock
Dividing plants to grow more requires the digging up of plants to divide into new sections that are then planted as new plants. These new plants need to be cut back drastically to prevent transplant shock and give the new plants a chance to grow. You can also cut back trees and shrubs that need to be moved to a new position in the garden to reduce shock.
Increase air flow and reduce infection
An increase in air flow between branches or stems of a plant will also help prevent pests and diseases. You can reduce the spread of infections by removing any diseased branches immediately and destroying them before any infection is able to spread to the rest of the plant or to another plant. Increased air flow will also reduce possible fungal infections.
Control Size
This is by far the most common need for pruning and it’s all about size. Vigorous plant growth can get out of hand and a regular pruning schedule is the only way to keep some plants in check and not crowd over others in their vicinity.
Prevent safety hazards
Damaged or broken branches can become a safety concern especially in large trees and it’s best to deal with them timeously to avoid the possibility of someone being hurt or the chance of property damage.
Shape and enhance aesthetics
A well-manicured garden will often rely on pruning to maintain good plant shapes. It is also a monthly task for formal gardening shapes like hedging, topiaries and espaliers that can’t be formed without pruning.
READ MORE: Get Your Blades Out! Spring pruning
