There are two types of tomato plants: indeterminate and determinate. Determinate plants are compact and bushy, growing to 4 feet tall. Indeterminate plants are also known as vining tomatoes; they can grow to 10 feet tall. There is a simple way to prune both types to keep the plants' sprawling growth under control and encourage fruit production.
Wipe your pruning scissors with a cloth dipped in rubbing alcohol to sanitize them.
Trim off any dead or broken branches.
Pinch the tips of the branches throughout the growing season to encourage the plants to grow bushy and full. Every time you pinch a branch, only trim off the last set of two leaves.
Trim back branches that are not blooming, as well as branches that are crowding one another. Don't trim too much; some foliage is necessary to shade developing fruit from the sun, wind and rain.
Grow your tomato plant on a trellis; it will be easier to prune and may grow faster. Growing the plant vertically also makes it easier to locate and harvest the crop.