I recently overheard a conversation while shopping for plants. The shoppers were discussing whether or not to prune their tomatoes. Pruning tomatoes can help some types produce more fruit. University of Illinois Extension educator Maurice Ogutu explains why below.
"Tomatoes are divided into two different types namely determinate and indeterminate varieties based on their growth habits."
The determinate varieties have short to medium vine lengths. Plants are heavily branched and growth stops when they start flowering. Every branch tends to end up with a flower cluster. The determinate varieties can be staked or caged but not trellised. Determinate varieties are not heavily pruned as most of the fruit is produced on the branches. Some of the determinate varieties are Celebrity, Bush Steak, Mountain Pride, Rutgers, and Super Tasty.
Ogutu said the indeterminate varieties continue to grow and produce leaves and flowers until the first frost. They are heavily pruned when trellised, moderately pruned when staked, and lightly pruned when caged. Some of the indeterminate varieties are 'Better Boy,' 'Big Beef,' 'Big Pink,' 'Brandy Boy,' 'Brandywine,' and 'Floradel.'
Pruning is the removal of small shoots that join the stem," he said. "This reduces competition between the suckers and the fruit. Pruned plants produce larger, and an earlier fruit as most of the plant energy is channeled into the fruit."
Remove the shoots when they are four inches long as removal of larger suckers may lead to injury to the plant. Remove a sucker by grasping it between your thumb and second finger and bending it to the side until it breaks. It is advisable to do this early in the day when the plant is still crisp. Do not cut suckers with a knife as this can lead to spread of diseases. Limit the branches of indeterminate varieties to two to three fruit producing branches by selecting the main stem, the sucker that develops immediately below the first flower cluster, and another sucker below that. Remove all other suckers, and periodically remove new suckers that form on the selected branches.
"It is important to decide on the type of support before setting plants in the garden," Ogutu noted. "Plants that are to be supported using trellises are set closer than plants to be staked or caged. Plants to be caged are set further apart than plants to be staked. Alternatively, you can choose the type of support based on how the plants were set in your garden."
For more information on growing tomatoes and other vegetables go to the University of Illinois Extension "Watch Your Garden Grow" website at https://extension.illinois.edu/veggies, or call the Master Gardener Helpline at (309) 685-3140 Monday through Friday from 9:00 a.m. - 12:00 p.m.