Backyard garden walls can be any length or height.  This one was positioned to offer a privacy barrier to the neighbour’s patio and outdoor table.  Walls have a growing surface on both sides.  Water can be harvested from roof tops and diverted to the wall with an irrigation line.  See Farm Garden Wall.  See video. See more photos below.

This wall takes up a very small space.

This garden wall has a small footprint.