ive got a 190cm hydro plant (not in a cabinet or anything) and its been budding now for almost 2-3months and it looks as tho the yeild ill get will be quite small, my plant has been through alot tho (spider mights, no water pump for 2 months, inconsistant temp and PH and irregular lighting) but i think the main factor is that most of the light wont reach the bottom half of the plant (unless u have lights on the side) anyway, just my cents. its just not efficient to grow a plant that big.