How and When to Prune a Tomato Plant

Pruning tomato plants improves airflow, makes harvesting fruit easier, and allows your plant to produce larger fruit earlier.

If you have a vegetable garden, chances are you have a tomato plant—or a few—growing in it. When home grown, the fruit bursts with flavor and produces a vibrant color that store-bought tomatoes just can't measure up to. While growing tomatoes in your backyard or on your balcony is a gratifying process, it's important to note that their care requirements go beyond just providing them with proper light, water, soil, and fertilizer. In fact, it's actually the removal process—or rather pruning—that's essential in helping the plant's overall health.

You may not think about pruning when you think of tomatoes because the vegetable can survive without this step, but our experts say that knowing how to prune a tomato plant can make a big difference in its productivity. The step will also improve its airflow, make harvesting fruit easier, and help your plant produce larger tomatoes in the long run.

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Why You Should Prune Tomato Plants

While the decision to prune your tomato plant is a personal one, Kelly Funk, president of Park Seed, says it can offer a handful of benefits, including improving tomato plant growth. "By pruning and keeping the plant tidy, it will focus on producing fruit instead of foliage," Funk says. "Pruning also allows the plant to produce larger fruit earlier." If the blossoming ends of the tomato are left on the plant, it will focus most of its energy into setting fruit instead of ripening the existing tomatoes.

How to Know If Your Tomato Plant Needs Pruning

While some tomato plants will greatly benefit from pruning, others will not. Before you start to trim, figure out which type of plant you have: determinate or indeterminate.

Determinate Tomatoes

Pruning determinate tomatoes is up to the grower, but it's a step that you can skip with this variety. "Determinate tomatoes are bush varieties because they do not produce continuously nor continue extending in length," Funk says. "These are for when you want a lot of tomatoes at once, such as Roma's for canning purposes." While determinate tomatoes don't need to be pruned since they produce fruit at one time, you may choose to anyway if you're the only person eating the fruit and want to limit the amount the plant produces.

Indeterminate Tomatoes

Unlike determinate tomatoes, indeterminate benefit greatly from pruning because they produce new leaves and fruit continuously throughout the growing season. According to Adrienne R. Roethling, the director of curation and mission delivery at Paul J. Ciener Botanical Garden, pruning indeterminate tomatoes will help keep the plants under control and prevent them from leaning and from over-fruiting.

pruning suckers off of tomato plant
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How to Prune a Tomato Plant

You should start pruning your tomato plant when it gets to be about 1 to 2 feet tall, which Funk says is usually when the plant reaches the height of the cage or stake that supports it.

Locate the Suckers

Before you get started, you should find the plant's main stems, which will have many secondary shoots or leaves, called suckers, growing off of them. "The secondary shoots are just that, you have a main stem—or three to four [of] what you consider main stems—and secondary shoots that emerge from the crotch of a leaf stem," Roethling says. According to Funk, you'll be able to easily spot the suckers by looking in the V-shaped spaces between the main stem and the branches of the plant.

Remove the Suckers

Once you've found the suckers, it's time to remove them. "Prune the tomato suckers to just above the highest fruit." Funk says. "Use a clean, sharp pair of pruning shears and snip them off." She notes that the suckers can also be snapped off with your hands if they are very young. Be careful not to remove the suckers all at once, which can put stress on the plant. Towards the end of the season, you should remove any excess leaf growth and branches that do not have any fruit on them to allow the plant to focus its energy on the remaining parts.

When to Prune a Tomato Plant

The best time to prune a tomato plant is in the early morning on a dry day. "Pruning wet plants can cause the spread of diseases," Funk says. Additionally, if you have a tomato plant that grew in a container and is ready to be placed into the ground, it's best to prune it when you it's ready to be planted, says Vicky Popat, CFO and tropical plant expert at PlantOGram.

Popat also says to make sure you're planting your tomato nice and deep. "This creates a stronger, healthier root system that will hold an abundance of tomatoes," she says. You can continue to remove flowers from your tomato plants until they are about 12 to 18 inches tall to ensure an even hardier root system.

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