There are many strategies out there for pruning or pinching tomato plants for better growth, production and health. But, before you start oiling and sharpening your pruners and snippers and charging to the tomato patch, do some research and assess what types of tomatoes you are growing.
There are two types of tomato growth patterns: determinate and indeterminate. Determinate varieties are shorter and produce most of their fruit at the same time. It is generally agreed it is best not to prune them or you will risk reduced yield. Indeterminates grow taller as they grow throughout the season, producing continuously. If you prefer to stake your tomato plants, leaving two side branches or ‘suckers’ will give you three fruiting stems and you will need three stakes for support. On your indeterminate tomatoes, remove all the suckers above that point by pinching them out with your fingers. They will start to grow on the diagonal where the side branches meet the main stem. This should keep the plant from getting too bushy and allow the plant’s energy to focus on producing fruit. Determinate tomato plants only need the removal of suckers below the first flower cluster. They have a predetermined number of stems, leaves and flowers hardwired into their genes.
On any tomato plant, it is best to remove the lowest branches to keep them clean and off the ground and increase airflow. If you are growing in cages, you may want to remove all the suckers to keep the plant from getting bushy. Consider clipping the growing tip on your indeterminate tomatoes to encourage the ripening of the fruit on the bush instead of producing more. This is best done about 30 days prior to the first frost date. However, if you don’t mind bringing your green tomatoes indoors to ripen, this wouldn’t be necessary.
So, what is the basic premise for pruning anyway? Removing extra growth redirects energy back to the fruit as well as reduces shading, both helping fruit to mature faster. By increasing airflow, the leaves dry more readily reducing the chance of fungal and bacterial disease. According to the University of Wisconsin Extension, it might be best to stop pruning a week or two before the first harvest, allowing canopies to protect the fruit from sunscald. As intense as the afternoon sun was last summer, this sounds like good advice. You may also experiment with shade cloth.
If you plan to leave two suckers for additional producing stems, the Wisconsin Extension recommends leaving the sucker below the lowest flower/fruit cluster on each plant. (Not the ones closest to the ground). That sucker is the strongest one on the plant and should be left to grow fruit as the second stem. They go on to say, remove the suckers early in the season so they don’t divert energy.
Other helpful hints: prune slowly and lightly so as not to stress the plant or cause sunscald; don’t prune when the leaves are wet; if a sucker is too big to pinch, use clean, sharp garden clippers.