New research explains why pruning encourages plants to thrive

Scientists have shown that the main shoot dominates a plant’s growth principally because it was there first, rather than due to its position at the top of the plant, ScienceDaily reported.

Researchers discovered that all shoot tips on a plant can influence each other’s growth. The study suggests that for a shoot tip to be active, it must be able to export the hormone auxin into the main stem. But if substantial amounts of auxin already exist in the main stem, export from an additional shoot tip cannot be established.

Professor Ottoline Leyser, one of the study’s authors, offered this explanation: “Using this mechanism, all the shoot tips on a plant compete with each other, so that tips both above and below can influence each other's growth. This allows the strongest branches to grow the most vigorously, wherever they may be on the plant. The main shoot dominates mostly because it was there first, rather than because of its position at the apex of the plant.”