This flower pot is a nice alternative to plastic or even clay. You collect old milk cartons and build a wall. Because of the tin foil, used in the milk carton, it is easy to store heat from the sun. Even in autumn Berlin times, plants can live longer.
The wall is located in Berlin Kreuzberg, at the entrance of BETAHAUS, a big Berlin collective office. Sadly it is used as an ashtray for the people working there.