Tower Garden® is a general vertical hydroponic growing system, although it is at times confused to be an aeroponic system. Priced at over $500 and weighing over 150lbs when filled, it is a patented food production system designed for urban farms, rooftop gardens, and commercial growing operations. Because of its vertical design, the system is space and energy efficient. The basic unit has a 2.5\' x 2.5\' footprint, and uses modular stackable growing pots. With an 11-pot maximum configuration, you can grow up to 44 plants per tower with 90% less space and water and in a fraction of the time compared to conventional gardening.

The Tower Garden® is made from hardened polyurethane. Additionally, the Tower Garden® product is designed for decades of use. The plastic is several times thicker than almost all hydroponic products available on the market today. The plastic is also completely opaque, keeping all sunlight out (which naturally inhibits algae growth), and is UV stabilized for outdoor protection.

-Wikipedia