I was thinking of building box, say 6, 7 ft. Closet size. With fixed compact flor. Keeping the plants on the shorter side and hanging some on the top, upside down. Have 8 at 30" plants instead of 4 at 60" tall. I don;t know.... i think it would work.

I would think you would need an immense number of CFL’s to cover that much height regardless of growing up or growing both up and down. It would take a lot of CFLs to give adequate lighting to a 5-foot tall plant, or 5-feet of plants made up of more 2 1/2-foot plants and get average or better production from that much production area. Someone would be better with a HID CoolTube.
　
One alone with a reflector, in the proper wattage of course, would handle the height requirement if you want production from the lower portions of your plants.

If grown both ways a same wattage CoolTube without a reflector then positioned in the center shining both up and down would work well and again you have adequate light to all portions of the plants.

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plants grow toward the light.. the roots may be doing all types of wild things up top in the dirt but who cares as long as your green is heading toward the light..

revenge of the plants on science channel not to long ago , about plants having a brain and such. you should look it up and watch it will show you alot that goes far with growing.

they showed plants have memory.. they laid them sideways, they grew at a 90 toward the light.. this is where i forget details.
but some point they let them relax and grow upright again in the dark. then they put them in a freezer to put them in a hibernation like state.
long story short when they thawed out and were put back under the light they remembered being on there side last and in the upright position started to grow sideways at the same 90 degree angle...

so i would imagine if you had them indoors and with an hps light the plant is going to grow toward that bright ass light regardless of what gravity has to say about it.. you might have to start it upside down once it is in the veg state for a few weeks

I'd be afraid of the water dripping through onto the lights. If you had a plastic bottom and put some rubber grommets on the base of the plant to keep it from leaking, it seems like it would work. Definitely post pics if you rock it out tho.

The grommets would be like the ones they use in this video.
http://www.youtube.com/watch?v=T07--heDYHc

I'm quite confident that this is achievable as a buddy of mine does it, some hanging full and some on the walls, he does it all in a big barn so of course he has room and it seems really fun : D