Prune your plants once a week. Always cut to side shoots and never cut the plant back to stubs. How To Grow Tomato Plants From Cuttings In 1 Week A Piece Of Rainbow Where does a sucker grow and how do. How do you trim back a tomato plant . Have you ever had a tomato growing too far out of control. Select a side shoot to prune back to at the desired height of the plant. Our favorite tomato variety. Once your tomato plants have reached 18 inches tall you can begin pruning or trimming them to help them direct more of their energy toward growing. As your plants fill out and grow you can prune more moving higher on the plant as you reach the full height of your tomato plant. Managing your tomato plants by learning how and when to prune them is one of the key secrets for producing a healthier and better crop of tomatoes. Would it be worth cutting it down and trying. Make Sure You Mulch Mulching. Httpsamznto3a9l1QXShould you prune Indeterminate or Determinate tomato plan...