Tomatoes can be grown in many sized containers. The 18 gallon storage container can handle 1 indeterminate tomato or 2 determinate tomatoes. This video shows you the basic set up but focus on 'replenishing' 2 year old soil. Egg shells, peat moss or organic matter and some fertilizer will prepare your container soil for the new season.
Planting Tomatoes in 18 Gallon Containers: Preparing the Soil & Egg Shells - The Rusted Garden 2013 - YouTube http://bit.ly/18cv7tp
Comment from Kyle Lester: If you are going to buy a container might as well be food grade I read this. The quickest and most reliable way to check for food safety is by consulting the recycling number. This number will be between 1 and 7 and will be stamped inside a triangle of arrows. As a general rule, the numbers that are safe for use with food are 1, 2, 4, and 5.