In general, tomatoes like to have a lot of space in which to grow, although that isn't the only consideration when choosing the best tomato pot for container gardening. Traditional pots that sit on the ground work very well when they are large enough to support a tomato plant and have been prepared correctly. Hanging pots generally are not practical, with the exception of an upside-down tomato pot, which can have various levels of success depending on where it is hung and how it is used. Self-watering pots can help to give tomatoes as much water as they need while growing, but they can require more maintenance that other pots and sometimes can give a false sense of security. It is possible under the right conditions to grow tomatoes in a window box, although the amount of fruit that grows might vary greatly.
When choosing a traditional planter as a tomato pot, there are only a few factors to look for. The plants, whether determinate or indeterminate, generally will be the happiest and produce the most fruit if planted in about 18 to 32 inches (about 46 to 81 centimeters) of open space, so the planter should be at least 18 inches (46 centimeters) across for a single plant, although it is possible to crowd two or three of some varieties in a single pot. The pot also should have a drainage hole in the bottom, or one should be drilled. The pot will work best if gravel, broken pottery or some other substance is placed in the bottom to allow water to drain from the soil.
An upside-down tomato pot is one that hangs from a hook mounted in a high place. These are a good choice for growing tomatoes in small areas, in cities, or in places where pests make it impossible to use the ground. Not all upside-down planters work for all people, and some individual plants might not take well to growing downward, causing the tomatoes to put out a lot of green growth but no fruit. These pots also may be problematic, because they need to be watered from the top; if it is hung too high, a ladder or stool might be needed to water it every day.
A self-watering tomato pot looks like a normal pot, except that it has a small reservoir in the bottom that can be filled with water so the water can evaporate and be absorbed into the soil, where it wicks upward toward the roots. These are a good choice for areas where summers are hot and dry. Even though the tomato pot is self-watering, though, the reservoir still might need to be refilled more than once a day, depending on the weather.
It is possible to use a window box as a tomato pot. The plant will more than likely have to be staked at some point, and the roots might become bound later in the season, but the plant will grow. One complication, however, is that the soil in a window box tends to dry out faster than other planters, and the less water that the tomato plant has, the less of a chance it has of producing fruit and keeping its blooms. A better solution for a window box tomato pot would be a deep, self-watering window box to counteract the dry, warm air that will circulate around the sides.