Although determinate tomatoes are compact and need little pruning, indeterminate tomatoes can produce 10 or more stems and may spread over 16 square feet. The excess growth consumes energy, shades older growth and results in smaller, insipid fruit. To control this excess growth, you must remove the leafy suckers, redirecting the plant's energy into fruit production. Removing these leaves from tomato plants creates stronger plant structure and larger, sweeter tomatoes.
Locate the leafy suckers before they are over 3 inches long. These are leaf buds growing in the crotch between the main stem and the primary leaf branches. Neglected suckers may be large.
Pinch smaller leaf buds with your thumb and first finger. Bend the sucker back and forth until it snaps off. Removing very large suckers may shock the plant. Instead of removing the entire overgrown sucker, remove the growing tip, leaving a few leaves behind.
Remove older, tougher suckers with a retractable knife. Compost or dispose of the cuttings to prevent disease. Monitor the cut for signs of infection or decay.