Is there any general rule of thumb on topping your plants? I'm dealing with a box height of 4', so I'll have to groom my plants. I've read on the good strains that topping is good and is not good. Any advice?
Size of the space, indica vs sativa and how many plants you want to have in the space all play a part in choosing whether or not topping is going to be the right approach. If you want to keep plant numbers down you could top a plant and tie down the branches while it is vegging (Low Stress Training). That way you can grow a large, uniform plant who's canopy can be as large as you want.