Pruning is the removal by trimming or cutting off parts of a plant that are old, dead, diseased or not needed for a plants growth, or whose continuous presence can be injurious to the plants health.
Reasons for pruning
Why do we prune plants?
Plants are pruned to maintain good health. If a plant becomes too dense or bushy, it is likely that air circulation within the shrub will be lacking. This forms dark, damp spaces that encourage pests and diseases.
In the course of growth some plant parts become diseased or die off. These are removed during pruning so the plant doesn’t waste energy sending food to dead parts. Pruning is also done to encourage growth of vigorous bushy growth. A plant that looks lethargic can be reenergized with a heavy pruning that spurs fresh new growth. Strong young growth is desirable for production of quality flowers and fruits.
How to prune a plant
When you want to prune, first assess the overall shape of the plant. Start off by cutting down any diseased, dead, dry or damaged wood. This will promote good health.
Second cut off any inward facing branches. Branches are supposed to grow out, not into each other. Inward facing branches create a dense, dark environment which fosters diseases and pests. Ideally a plant should grow out like a glass-narrow at the bottom and widening at the top with space for air circulation within the foliage.
Keep in mind that a healthy plant, when pruned harder grows back more vigorously. Similarly if you prune, lightly the regrowth will be limited.
Principles of pruning
Plants are pruned principally to achieve there purposes; format the plant, restrict its growth or renovate/renew the plant.
Formative pruning
Formative pruning is done in order produce a sturdy plant with well-balanced framework. It aims to have well-spaced branches for air and light to reach the whole plant. Shrubs like Hibiscus require light formative pruning to ensure balanced growth. If you have deciduous plants, the right time to prune them is either at or soon after planting when they are dormant.
At the onset you can train your young shrubs to have a balanced framework. Cut back severely, and then select 4 branches that are evenly spaced to form the new framework. Remove all the other branches.
Note that not all plants require formative pruning.
Restrictive pruning
Restrictive pruning is done to prevent a plant from encroaching on to a space it is not supposed to occupy. While it is always good to allocate a plant in a space it will fit, it is not always possible to know the eventual size of a plant. Restrictive pruning tends to be more severe so that the plant does not regrow fast to cause the same problem. Like in all pruning strive for a balanced well-spaced open framework.
Renovation/renewal pruning
For old plants or shrubs that produce new growth from the base or from old wood, they can be rejuvenated by hard pruning. Overgrown shrubs too benefit from renewal pruning as a drastic cut down to 30-45 cm above the ground spurs new formative growth. Pick 4 healthy shoots that will sprout from each stem to produce a new framework. Cut out the rest.
Sometimes it is better to stagger the pruning over two years so that the place does not remain bare.
Whatever reason you have to prune, always make sure your tools are clean and the blades sharp. Blunt tools make ragged cuts that take long to heal and can be potential entry points for infections. Secateurs are best deployed for cutting small branches of up to 1 cm diameter. For larger branches use pruning saws to avoid crushing plant tissue.