Also, there are reasons why pro and commercial growers don't grow 16 foot high plants indoors under artificial light.
Plants that tall can do well under SUNLIGHT, which is very bright, and moves across the sky to ensure that the entire plant gets direct light. If you want to plant a "tree" you have to do so outdoors (or at least in a greenhouse).
Indoors, the problem is that the tops of the plants near the lamp will get lots of light, and the bottoms will be 10+ feet away and won't. You'll get a few nice buds on top, but the other 14 feet of plant will develop airy buds, effectively "wasting" most of the plants potential.
This is why indoor growers who grow sativa dominant plants try to keep them short, either by going 12-12 from seed to harvest (to minimize unnecessary vertical growth) or by training their plants in SCROGs and such, to help maximize light on all parts of the plant for high yields.