The Dutch artist Anne Chienmeier has already done small gardens on the bus roofs and airplanes. And her last project is movable community garden. Citizens can take it directly to their front door, or park it on a suburban industrial zone and pick fresh vegetables for lunch, and drive it away when winter comes. But more than fresh vegetables important is community sense, meet and talk to neighbours, cultivate together, celebrate garden celebrations and eat the cultivated crop together.
You can read about Annechien Meier, her Mobile garden project and more other projects (but in Dutch) in her web page.
Info from www.nextnature.com