[smogcutter]

I’d love to be corrected by a more experienced gardener, but my understanding is energy that a plant puts into growing leaves and stems is energy that isn’t going into growing fruit. This is part of the reason for pruning plants, which otherwise seems counterintuitive.

[jmheflin]

Correct, young leaves are BIG carbohydrate sinks until they have expanded and begun to produce their own photosynthate. Pruning off new growth allows the plant to redirect carbohydrates into existing organs.

There are a few leaves around the grape cluster that supply sugar to the cluster. The rest of the leaves do not contribute to the growth of the cluster.

[tipoftheiceberg]

Search ‘plant hormones and their functions’