I've heard of ppl growing a few plants in trees before.

I did a quick search and found these tips:

"More sunlight is available near the tops of the trees in dense forest. Ingenious growers use deer/elk hunting stands to grow in trees. They set up a pulley system to lift a large container and potting soil up to sit on the plant stand. Install an irrigation hose from the bottom of the tree directly to the plant. The grower passes by weekly with water and manual or battery operated pump to lift water to the plant high in the tree.

A partner is necessary to work on the ground while the other person works in the tree. Smart growers use a safety line and belt and do not spend more than 4 hours off the ground in one day. Accidents happen to tired climbers."

I did another search, cuz this topic amuses me, and I found this other guy's grow log about how he's growing 7 plants up a 75 ft pine tree.
Growing in a tree - Marijuana Growing

(dear mods, I'm unsure if posting links to a competitor's forums is allowed. If it isn't, please delete my post, accept my apologies, and please inform me so I don't do it again.)