I know folks who get an average of 4 lbs of dried buds per plant growing Purple Kush. They normally fertilize with every watering but they had a wake up call last summer. One of their trees (some yield up to 7 lbs of dried buds) started suddenly wilting and dying even though it had been adequately watered. They had another guy come by and take a look and they decided the plant was getting too much nutrients and was shutting down. It would have died within a week if they did nothing. So they got the flush product the folks use at the end of the season to flush the nutrients out poured it on and watered the daylights out of it. They saved the plant but it never fully recovered and ended up being the smallest plant.

If you use nutrients with every watering make sure not to over do it.