Unlike most climbing and trailing plants, which are allowed to grow unchecked, plants with a more rounded habit need to have their growing tips removed regularly to encourage bushy growth.
The natural growth regulating hormones of a plant are found in the highest concentrations in the growing points of the shoots, where they act to suppress competition from the other buds down the stems. If these tips are removed, the hormones in the other buds are triggered into action, producing a side shoot from almost every leaf axil — known as “bushing.”
In nature, this is intended to provide another leading shoot to assume dominance, but it can also be used on domestic plants to encourage them to form dense, bushy growth. Manipulating growth in this way is known as “pinching” on a younger plant, when it is usually carried out with the finger and thumb, but it can also be used to encourage climbing plants to produce multiple stems. Pruners are often used to trim older plants all over in a process known as “tipping” to keep them growing to the required shape.
“Pinching out all of the main growing tips on a young plant, after flowering, helps produce plenty of even growth, rather than a few dominant shoots.”