These are actually Grandma's, but I'm counting them since they're at my house currently! I need to do this for sweet potatoes!
Grandma found brand new trashcans for $10 at a local box store. With the assistance of my husband and his tools, she has three holes cut in the bottom of each of these cans, and a few holes on the sides about two inches up from the bottom. After washing and sanitizing the cans we placed coffee filters (on hand for brewing joe for roses and for when MIL visits) over the bottom holes and added some soil.
Then the seed potatoes were planted.
As the potato plants grow, more soil can be easily added. According to the article that gave Grandma this idea, one can get about a half-bushel of potatoes per garbage pail. It's less mess than some of the garden plot or pallet ideas, and it's not as health-hazardous as the used-tire ideas. It's a space effective container garden, eh? *lol*