In cannabis, the main growing tip at the top of the plant is where the strongest buds form. With correct pruning, you can split this growing tip into 2 or more. Pruning can also help you to control a plants overall size, shape and yield. See Cannabis pruning and training from here.
PRUNING AND TRAINING
Bending or training your plants has the same effect as pruning in that it will encourage more growth lower down. Because it’s less traumatic to the plant it can be carried out even in full flower, it may however increase the flowering time by a week or two.
Major pruning should take place a week or so before flowering is induced. After this limit pruning to removal of weak stems that do not receive much light and any damaged or dying leaves. Do not remove healthy leaves.
Most un-pruned commercial plants grow into the classic Christmas tree shape. Pruning to outward facing growing tips however will encourage the plant to grow into a goblet shape, this opens up the plant helping to increase air and light penetration.
A branch is an ever repeating pattern, if you split it into 2 it will repeat its growth pattern in 2 or more places. Once cannabis is put into its flowering cycle it will usually grow to around 3 times its original size (30 cm plants finish around 90 cm tall).
Indoors plants are best kept short (90 cm max when finished) and pruned to no more than 6 main growing tips. Too many tips on one plant can result in an overall drop in it`s potency and a lot of small fiddly buds that are hard to prune.
Outdoors light intensity does not diminish in the dramatic way that it does with artificial light. Lower branches receive the same amount of light as the tops. Outdoor plants can therefore be larger, bushier and support more flowering tops.