Pruning can be tricky and for the beginning gardener, a bit scary. Proper pruning of your plants, however, will ultimately lead to stronger, healthier more productive plants. The trick to this is having some initial understanding of why we are pruning, what we’re trying to achieve and how best to go about it. In our vegetable gardens, production trumps almost all other motivations for pruning. So understanding how to prune and shape plants to maximize yield is our goal.
Pruning for Optimal Yield
How to Prune for Optimal Growth
It’s important for the development of a healthy, productive plant to encourage a robust, well developed structure. This is often achieved early on in the plant’s development with a technique known as topping-off. Topping off refers to the practice of removing the main, or leading, stem once the first two lateral branches have developed. This is done to remove apical dominance, the phenomenon where the main, central stem of the plant grows more strongly than the side stems. Removing apical dominance forces the remaining growth points (lateral branches) to produce and grow faster. Apical dominance is controlled by the production of a plant growth hormone called an auxin which also inhibits and slows the growth of side branches and lateral shoots.
Removal of this dominant shoot promotes better growth throughout the rest of the plant, resulting in new lateral shoots that are denser and more vigorous. The lower branches and structure of the plant become more robust instead of being restricted by the apical dominance of the main shoot. The result is a plant that has a more full-bodied vascular system. The channels and pathways leading into other parts of the plant develop bigger than they normally would have become, which is why the excessive pruning of annual fruiting plants is so successful. Forcing the plants’ vascular systems and structures to grow bigger also signals fruits to develop bigger.
How to Prune: Once the initial 3 or 4 true leaves have formed, a plant can be made to possess 2 or more main stems by removing the ‘terminal growing tip’. The new main stems will grow from the ‘axillary buds’ located at the remaining leaf nodes. For many species, major ‘structural’ pruning should only be conducted during the vegetative phase to avoid stressing plants by pruning during flowering. Plant stress can be minimized by conducting major pruning in stages. For example, allow plants to rest for a week or so between prunes.
How to Prune to Maximize Fruit Size
How to Prune: For most fruiting annuals, it is important that all shoot growth be halted at the beginning stage of flowering and fruiting growth. This will help ensure there is no competition for immature young fruitlets. Also, helping the fruit or its truss grow and have its cells divide for a longer period time is critical. Pruning your plants after pollination increases the length of time cells divide in the fruit, which means bigger fruits. It is also important coming into the fruit development stage to thin an overcrowded plant to allow the plant access to more air and light. In tomatoes this is easily done by removing suckers, then removing other unhealthy, damaged or old branches that are unnecessarily consuming valuable nutrient resources.
Removing dense growth will allow better airflow and light penetration throughout the foliage. This will enable fruit to ripen more quickly.
Broken, dying or dead growth is susceptible to disease and pest attack and therefore should be promptly removed from the plant and the growing area.