When I was 14 I grew my first plant on the roof. There was a huge plant growing along side the chimny all the way up. I hollowed out a hole in the middle of it and put a small piece of plywood inside. Then I put my plant on it. I didn't know what I was doing and grew it in a 1 gallon pot to finish but it had some beautiful purple buds. It was about 3 feet tall when finished.