Might want to read-up on growing cannabis. This is an advanced technique requiring you to recognize deficiencies, knowing how and when to perform certain tasks, and the grower needs an overabundance of patience and diligence. If growing for personal smoke, you might want to reconsider performing harsh bonsai techniques on seedlings, as the yield is greatly diminished, and after chopping the roots, difficult to keep alive.

A bonsai technique is in my signature, but it is part of a re-vegging technique, excellent for harversting clones.