Glancing back through the thread, I didn't see what strain that plant is, or if it came from a clone or seed. It seems as though your plant grew well without any serious problems so I would say try some different/better genetics. People don't seem to stress enough how important a good pheno is to producing serious weight. I grew 5 different phenos last grow, and 1 plant produced as much as all the other 4 combined. This grow is only that strain in my little 2'x3' cabinet and I should outyield your plant while only using 285 watts. Not because I am a better grower than you, but this pheno kicks ass.
The strain/pheno you grew may just not be a great yielder. Your plant still yielded around half pound which isn't bad, but on a grams per watt + considering the time in veg, it could have been quite a bit better. I would think a pound+ would be reasonable to expect with that much light. Don't give up.
