I tried growing tomatoes in a 5...

Tomatoes need a lot of space. If you want to use containers, the half wine barrels gardening stores sell, or anything that is about the diameter of a 50-gallon garbage can, work best. Actually, using a garbage can itself might be a good idea. Whatever you use, make sure you have plenty of drainage holes in the bottom. For smaller types of tomatoes, such as cherry or grape tomatoes, a 16- to 20-inch-diameter container should be fine. Tomato plants grown in containers require more water and fertilizer than in-ground plants. Water plants when the top three to four inches of soil is dry. Avoid wetting the foliage, and soak the soil until you see water draining through the bottom of the container. After the plants begin to set fruits, water them daily, especially on hot, windy days. Fertilize regularly with any all-purpose fertilizer.