Allemende Kontor, a Berlino, it’s in a public space, in a wide area. The vegetable gardens anyway are not in the ground, but in container, pot, baskets…. 
Tempel Hof the public park where Allmende contor (which means public office) is, it was an old airport. It was the oneo which was used at the end of World war II, starting cold war, to bring aid to western Berlino isolated by sovietic army. The access to the garden is totally free: you can go there, build your container, put your name in it, and share your knowledge with other people. There is an association, wich signed a contract with the council, but everyone can go, do and help.