We have shown a lot of green wall systems that require some pretty complicated plumbing and controls, with the plants barely hanging on to a layer of felt or mesh. Christopher Lyon of Tournesol Site Works has an interesting alternative, a prefabricated system out of Singapore that has enough depth to hold a serious amount of soil. It is a lightweight plastic version of Sharp and Diamond's modular wall system seen at the Vancouver Aquarium, where modular boxes can be pre-grown and just fastened to the wall on rails. If one dies back you just pull it out and replace it.
The system is so new that it is not even on the website yet, but watch for it at Tournesol Site Works.
Other Green Walls on TreeHugger:
11 Buildings Wrapped in Gorgeous Green and Living Walls
Temporary Living Wall for Construction Site
Topiade by Gas Design Group for Louis Vuitton
Interview: Oulu's Designer, Evangeline Dennie