Understanding the when, why, and how of pruning tomatoes for the best yield
To prune or not to prune tomatoes, that is a question that backyard tomato growers need to answer for themselves. Growing strong, healthy tomato plants increases the chance of getting a large crop of delicious tomatoes. The careful pruning of tomato plants during the first few months of the season will help to achieve this goal. Pruning allows the plant to direct its energy into producing fruit rather than excess foliage. It also promotes increased airflow which reduces the humid conditions that favor fungal and bacterial growth.
Prune based on variety of tomato
There are two basic types of tomatoes: indeterminate and determinate. Indeterminate tomatoes, which include most heirloom tomatoes, grow like a vine and produce fruit throughout the growing season. Determinate tomato varieties, such as Martino’s Roma, tend to be smaller, bushier plants that produce most of their fruit in a shorter period of time. Both types of tomatoes benefit from the removal of all leaves and branches that touch the ground. This helps prevent the plant from contracting fungal and bacterial diseases.
Pruning indeterminate tomatoes
Training indeterminate vining plants to one or two major stems, called leaders, keeps their wild growth under control and allows the plant to produce bigger tomatoes that ripen earlier. This is accomplished by removing all leaves below the first flower cluster for a single leader and pinching all suckers that grow out of the V junctions above this cluster. For a double leader, establish a strong Y by allowing the sucker right below the first flower cluster to grow into the second stem but remove all additional suckers as the plant grows.
Pruning leaves and suckers of tomato plants
Leaves and suckers can be removed by pinching with your fingers or using shears or clippers. Before and after pruning, be sure to thoroughly wash your hands with soap and water. If you choose to use shears or clippers, disinfect them with alcohol or a 10% bleach solution. For protection against sunscald, you can leave the first two leaves on each sucker and pinch the growth tip above them.
Pruning determinate tomatoes
Determinate tomatoes do not require the intensive pruning that indeterminate types do since they are a bush tomato and once they reach a certain size, they stop growing. The suckers can be allowed to remain and will grow to produce branches that bear fruit. Remember to remove any leaves that touch the ground for health reasons.
The final decision on whether to prune your tomato plants and how to prune them is one based on the tomato varieties grown and personal preference. Regardless of what method, and to what extent, you choose to prune your tomatoes, remember to always follow the basic three Ds of pruning: remove all Dead, Damaged, and Diseased leaves and dispose of them properly. All diseased plant material needs to be thrown in the garbage and not composted.
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This article originally appeared in the 05-28-2025 Mountain Democrat and was written by UC Master Gardener of El Dorado County Deborah Valerga.