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Growing Tomatoes: How to Prune Tomato Plants

Pruning tomato plants is an optional gardening task, but proper pruning can help prevent disease, produce more fruit, and help speed up ripening. Pruning is most effective when done throughout the entire growing season, so understanding the basics before you plant will lead to the best results. 

An Important Note About Tomato Varieties

Before you start planning and pruning, it is important to understand that tomatoes come in two different varieties, called determinate and indeterminate. Determinate varieties have a fixed form and defined mature size. They are often referred to as “bush” tomatoes. This type of tomato plant will remain fairly small and compact and the fruit will ripen all at once. You generally should not prune determinate varieties because it will likely reduce your overall harvest.

The majority of tomatoes grown and for sale are indeterminate, meaning they will continue to grow and produce fruit throughout the season. They may be referred to as “vining” tomatoes and include favorite varieties like beefsteak, big boy, sungold, and most heirloom and cherry tomatoes.

Benefits of Pruning Tomatoes

Indeterminate tomatoes benefit from pruning in many ways. More specific details are given throughout the article, but some of these benefits include:

  • Better airflow
  • Leaves dry faster and are less susceptible to disease
  • Prevent diseases caused by splashback
  • Less dense plants are easier to check for pests and problems
  • You can get larger fruit by directing the plant’s energy toward fruit production
  • Allows for taller plants that can be grown closer together to conserve space
  • Fruit can be made to ripen faster, if necessary

Pruning at Planting

When you first plant your seedling tomatoes, it is helpful to remove the lower leaves of the plant so that you can bury it deep in the ground. Tomato plants will produce roots all along the stem, so burying it deep will produce a better root system and stronger plant. Remove the lower leaves by pinching them off at the stem with your fingers or using snips or pruners for larger ones. It is also good to pinch off any flowers so that the plant’s energy will go toward leaf and plant growth during this stage.

Early to Mid Season Pruning

As your tomato plant grows, you will want to continue to remove the lower branches that are close to the ground. There are many diseases, including septoria and early blight, that live in the soil and can enter from water splashing on the leaves. Eliminating these bottom branches also allows the air to easily flow through and dry off the leaves, preventing bacteria and fungal pathogens from developing on your plants. To prevent disease, you should only prune your tomatoes with clean pruners and when the plants are dry. 

You may also start noticing side shoots that appear in the crotch between the main stem and the branches, an area called the axil. These new leaf growths are known as suckers. Pruning these is recommended because they will cause the plant to devote extra energy to them and away from the main stem. When the suckers are small, it is easy to pinch them off with your fingers. If they are allowed to grow for too long, they get larger and will need to be cut off with a sharp, clean pair of pruners so that damage to the plant is minimal. It is also recommended to continue to remove any flowers until the plant is 12-18 inches tall and is strong and healthy.

Late Season Pruning

As the growing season starts to wane, you may want to give your plant a chance to ripen the tomatoes that it has already produced instead of trying to produce more. You can help this process along by “topping” your tomato plant. This is typically done 3-4 weeks before the first frost by cutting off the growing tip from the main stem. Doing this will cause the plant to stop flowering, and it will start to direct all its energy and sugar toward ripening the fruit. This can be very beneficial for folks in northern climates with a shorter growing season.

Growing the Best Tomatoes

If you need some extra guidance about how to prune tomatoes, check out our video series on Growing Monster Tomatoes. You will learn everything you need to know from our expert gardener, including the best tomato fertilizer to use. Visit today for more tips and products that will help you grow amazing tomatoes and produce.



Photo Credit

Tomato suckers by Cheryl (CC BY-SA 2.0 via Flickr; identifying circles added