Examine the tomato plant for any suckers growing off the main shoot. To ensure your tomato plant remains healthy and strong, the Connecticut Agricultural Experiment Station recommends removing all suckers.
Wait until the tomato shoots at least 4 inches in length before grasping the sucker near the stem's base between your thumb and forefinger. Gently twist and bend the sucker until it breaks free of the stem. The University of Illinois Extension recommends removing the suckers first thing in the morning while the tomato plant is still crisp and cautions gardeners against cutting away the suckers with scissors or shears to avoid spreading disease.
Continue removing all the suckers by gently twisting them off with your fingers until they're completely eliminated. Throw the suckers into a plastic bag and discard them in an outdoor trash receptacle.
Monitor the tomato plant through the entire growing season. Twist off any emerging suckers in the same manner.