The varieties you planted might be the problem. There are two categories of tomatoes-determinate and indeterminate. Determinate tomatoes begin to set earlier than indeterminate, and stop growing when they reach a certain size. They're preferred by many gardeners. Indeterminate varieties continue to grow and set tomatoes as long as weather permits, and they may grow for a longer time before they begin to set. Once started, they can produce prodigious amounts of tomatoes, though. The classic example is the old type of cherry tomato, which can cover the side of a house if it is given enough space, support, and time. Overly vigorous tomatoes can also be the result of too much water or fertilizer. Instead of using a high-nitrogen fertilizer, try something light, such as fish emulsion. Also, cut back on watering when ripening starts, to encourage the vines to ripen the crop faster and to slow vine growth.