Your question has very many answers depending on a few things.
What strain is it?
What system are you growing in?
What stage of growing are you at?
What is the root system like?
What Nutrients and additives are you using?
Probably one of the things to look out for the most is the inter-nodal spacing. The correct use of light and temps can really affect this and its one of the things a lot of people overlook.
If you give us some more info on the above questions then I will do my best to answer your questions..
Stay cool,
Doobz