By the time July rolls around, the tidy little tomato plants you planted in the spring can begin to look a little ragged, with yellowing and brown, dying leaves at the base of the plant. When you snip off unhealthy parts of your tomato, it responds by putting its energy into producing healthy foliage, flowers and the fruit you want. Dying foliage can be a natural occurrence or it can be the result of plant diseases or insects. Whatever the cause, when you prune off dead and dying leaves and branches, your tomato plant benefits.
Allow your tomato plant's soil to dry out before you begin. The environment around wet soil is more likely to spread diseases.
Mix a dipping solution for your clippers by combining 1 part chlorine bleach with 9 parts water in a bowl or small bucket. When you wipe the blades after each cut with a clean rag, any diseases the plant might have will not spread to other parts of the plant or to other tomato plants.
Prune dead and dying leaves and branches first. Make the cuts at the base of the leaf or branch as close to the main stem as you can without cutting into the stem. Don't forget to wipe your clipper blades with the bleach solution after each cut.
Cut back sprawling branches of indeterminate tomato varieties if you want to keep your plant compact and tidy. Try to avoid cutting off flowers and any forming fruit to ensure that you'll get a good harvest later.
Prune suckers that grow from the base of leaves if you want to encourage strong growth of the main stem and lateral branches. This is important for large varieties of tomatoes, such as the Beefsteak types.
Place your trimmings into a garbage bag and dump it at your landfill. If you compost diseased trimmings, you might spread diseases.