Why so tall? The bestest reasons are
1. In the middle of your 1/4 ac in thick woods or next to barn, a mere 20 foot circular bldg, in a 45'x 65' clear-cut in thick woods, u can grow, stealthily, 72 plants that rap around and up.
2. U can completely control every grow-medium method when stacked in a huge PVC pipe. Every 8" tall a 4" hole allows u 2 catch the divider&glued, add your supersoil, perlite&h2o polymers, DWC, aquaponics, whatever. Insert seedling or clone thru hole that you've gifted it with your magical medium, allowing them to stretch 10' out all directions so a 20' diameter 1"PVC pipe, wood, steel, vertically ground to roof. If 40 degrees apart there's 9uprights. That'd have ladders (framing support) that your limber 100-150 lb friend plays monkey inside this 50' tall round greenhouse. Stealth 72 different strains, together in 16k cubic ft, as a state legal caregiver for 5patients plus myself, quite possibly the most lenient and least bureaucratically combobulated state to grow in, MI. Dangling 8' T12's, cfl's, hps for first and last 3hrs everyday since SUN isn't overhead & its in thick shady hardwoods.
3. Rinse and repeat 4 times per yr. Since nearly all strains/hybrids of, can be finished within 70 days X 4 = 280 days growing. U can even get long flowering sativa's started2-3wks, then transplant here.lol.
why so tall? why not? If I can legally grow inside a 60' tall greenhouse I can give each plant more like 10 gallons ea of medium