How I Prune Tomato Suckers! Let’s keep it simple. Pruning off suckers keeps an indeterminate tomato plant manageable. If left to grow, suckers will essential become another main stem that will produce leaves and fruit. I personally grow my tomatoes very close together and prune them to keep one main stem. My goal is to grow a large variety of plants to get a variety of fruit. If I had more space, I would allow each plant to grow 2-3 main stems (allow 1-2 suckers to mature early on along with the