Average Dimensions

• An average-sized tomato plant root extends from 2 to 2 1/2 feet in every direction around the stalk. It also runs to a depth of more than 3 feet. In all, an average tomato plant's root system takes up about 65 cubic feet.
  
  

Specific Dimensions

• About half of a tomato plant's roots are 4 inches long or less. The upper roots spread out horizontally the most. At about 11 inches below the surface, the roots stop spreading out and instead turn sharply downward.
  
  

Transplanting

• The easy growth of the tomato root system causes transplanting them to make them stronger. Every time you transplant them, bury them a little deeper than before. The newly buried section of stem will send out new roots, making the whole plant stronger.