You don’t have to prune your tomato plants for an abundant harvest, but pruning may have its advantages. By removing select branches, you'll increase the amount of sunlight filtering through the plant, which can potentially lead to larger fruits. More importantly, less foliage means increased airflow between branches which will allow the leaves to dry faster, slowing the growth of pathogens.
DETERMINATE -OR- INDETERMINATE
If you'd like to give pruning a try, before you begin, it’s important to know whether your plant is determinate or indeterminate. Determinate tomato plants are generally not pruned because they reach a fixed, compact, size of around 4-6 feet and set all of their fruit within a two week period (roma tomatoes are a good example). Removing branches on determinate tomatoes will cut into your potential harvest.
Indeterminate tomato varieties, on the other hand, are vining plants and will continue to grow and set fruit throughout the entire season. Most tomato varieties are indeterminate. If branches of these varieties are not pruned, they can become unruly, crowding the plant and competing for nutrients. Pruning branches happens by removal of the suckers (the growth that appears in the crotch, or ‘V,’ between the stem and a branch). If the suckers are left to grow, they will become another main stem with branches, flowers, fruit and will produce more suckers of their own.
STEPS TO REMOVING SUCKERS
REMOVING OTHER FOLIAGE
For both determinate and indeterminate plants remove the lower 12-18 inches of leaves and branches from mature plants. This will reduce the risk of soil-borne diseases from splashing up onto the leaves. In addition, snip off any diseased or damaged leaves or branches.
If you decide to try out pruning this season, just remember that less is more! Observe how your plants respond, take notes, and make adjustments the following year.