"It could be over fertilization, but more likely it is due to the pH being off. Too high or too low a pH can lock up nutrients in the form of undisolvable salts and compounds, some of which are actually toxic to the plants. What then happens is the grower then tries to supplement the plants diet...
I usually just let them grow in with the rest of the indoor garden. Just be sure to bring them out side just before solstice. I have found that the roots go deeper, thus the canopy gets bigger too.
I've been using vf11 for the last year and a half and it's all i use for blooming. I grow in dirt, and have used foxfarm in the beginning but I had to b e really careful with nute burn. With the vf11 they grow bigger with no burn. I grew two identical clones with each and the vf11 was much bigger.