The aquaponics and hydroponics guys use these all of the time. They are easy to build.
One caveat, they need to be drip watered as the plants will have very little soil and
need a lot of water.
You could fasten a whole row of these to the back fence and grow almost anything in
them that doesn't have a long root, such as carrots. Tomorrow I will post a picture of
my grow towers, using a clothes hamper from Big Lots.