If you're concerned with height problems look into LST (low stress training) I'm trying it for the first time now and touch wood it's pretty easy. Basically you tie the plant down (you can do it lots of different ways, string, wire clothes hangers etc) and force it to grow short and bushy rather than straight up. Apart from it helping problems with limited height it also makes the plant grow several colas instead of just one and makes for more efficient use of you're lighting as the canopy of buds is more even.