I just found this idea in a facebook conainer gardening group that I belong to , and it looks like something that would be easy to do, and could be as large or small as you wanted it to be. The basic idea is to use those square containers that have the latticework type sides. I think they are called milk crates because milk used to come in this kind of container. Anyway, then you line the milk crate with landscaping material, like you buy in rolls and put on thee ground to keep weeds from growing. Fill the crate with dirt and potting soil, and then you can cut little slits in the sides to put the plant roots inside of the crate so that they cascade out the sides. You can stack up the crates to whatever amount you wanted to have. The idea is for strawberries; but I think that a person could also use this idea for things like lettuce, spinach, and maybe even cucumbers. Flowers could even be used, or mixed in with the greenery. I can see something like this with strawberries or lettuce, and petunias mixed in here and there for added color.