For real, and you make the title of this "Vertical Growing" in the Vertical Growing section? LMAO just sayin man.. huh... Well anyway, pretty rudimentary inspection of the topic, like 101 inspection would lead you to see that it's basically a primary focus on side lighting. Because the plant tends to grow taller than it does wide, and inside grow lights do not penetrate the canopy NEARLY as well as natural sunlight, this optimizes the opportunity of the plant to absorb the lumens of your bulb, increasing the g/watt ratio. I'm suffering from serious insomnia the past month and some and briefly thought a jacket hanging from a doorknob was Death come to get me, but that notwithstanding I hope I summed it up pretty well for you there.