The next best thing is here: Towers of vertical gardens! These towers are mostly made for cites. The first city to actually use these is Singapore. They are use to grow vegetables because Singapore imports 93% of their vegetables and thus need to make space to grow their own. Instead of having countless acres of farmland in a city area, they started to build up. The city has almost 40 tiers, and the single towers are just shy of 30ft. The plants are rotated through out the day so they get an equal amount of sunlight. These towers only need 0.5 liters of water to operate a 1.7 ton structure, and 60W of energy for a one day use. The company that makes the towers (Sky Green) is claiming that they are 5 to 10 times more effective that regular farms. The downside is that the vegetables cost 10 to 20 cents more per pound than imported vegetables. Sky Green is looking to increase the amount of tires from 120 to 300 towers by 2013. The company is hoping that this idea will help get production of vegetables to be cost effective.
This is a super tree which does the same thing