How to Prune a Tomato Plant for a Bigger, Healthier Harvest

If you have a vegetable garden, chances are you have tomatoes growing in it. When home-grown, the fruit bursts with flavor and produces a vibrant color that store-bought tomatoes just don't measure up to. And one way to ensure this plant keeps producing delicious fruit throughout the season is by pruning.

Pruning not only makes a big difference in your tomato plants' productivity, but it also improves airflow, makes harvesting easier, and helps your plant produce larger fruit. Ahead, we're sharing expert tips for how and when to prune a tomato plant.

Benefits of Pruning a Tomato Plant

There are many benefits of pruning tomato plants, including higher yield and improved circulation.

Improved Plant Growth 

One of the most notable benefits of pruning tomato plants is that it improves yield. "By pruning and keeping the plant tidy, it will focus on producing fruit instead of foliage," says Kelly Funk, president of Jackson & Perkins.

Increased Fruit Size

Pruning also allows the plant to produce larger fruit earlier, says Funk. 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. 

Increased Circulation

Pruning helps increase airflow around the tomato plant by separating it from nearby plants. This helps the fruits ripen and keeps the plant healthy, says Susan Mulvihill, organic gardener and author.

Reduced Disease

By removing lower branches that are touching the ground, you decrease the risk of your tomato plants contracting a disease. This is because there is the potential for soil-dwelling pathogens to easily move onto the plant’s leaves from the ground, says Mulvihill.

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 varieties benefit greatly from pruning because they produce new leaves and fruit continuously throughout the growing season. Pruning indeterminate tomatoes will help keep the plants under control and prevent them from leaning and over-fruiting, says Adrienne R. Roethling, garden director for Paul J. Ciener Botanical Garden.

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.

1. Locate the Suckers

Before you get started, find the plant's main stems, which will have many secondary shoots or leaves, called suckers, growing off of them. 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.

2. 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." 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.

3. Remove Low-Hanging Branches

When pruning, also check the plant's base for any branches touching the soil or that look diseased. As long as the tomato plant is nearing its mature height, go ahead and use your pruning shears to snip off the lower branches up to a height of about 12 to 16 inches from the ground. These leaves aren’t helping energy production very much at this point, and are instead restricting airflow that could lead to disease.

4. Stake or Remove Long Branches

If the plant has grown beyond the height of the cage, either stake the branches or remove them. "Look closely at each branch, see where the developing fruits are, and cut back the branch just past that point," says Mulvihill. "Remember that you can’t put a branch back on once you’ve removed it, so take your time."

When to Prune a Tomato Plant

The tomato pruning process will likely begin fairly early in the growing season—possibly June or July, depending on your growing zone. The best time of day to prune a tomato plant is in the early morning on a dry day as pruning wet plants can cause the spread of diseases, Funk says.

Common Mistakes When Pruning a Tomato Plant

Some home gardeners avoid pruning tomatoes because they’re worried about doing it wrong or making a mistake. Here are some common mistakes to avoid when pruning tomato plants.

Pruning Determinate Tomatoes

Cutting back the branches of determinate tomatoes will significantly impact the harvest you were going to get, says Mulvihill. Pruning is unnecessary because determinate tomatoes only grow to a certain height and then stop producing foliage.

Pruning Wet Plants

Funk and Mulvilhill both caution against pruning tomatoes while the branches are wet. “This can potentially increase the chance of diseases, which will in turn impact your harvest,” says Mulvihill.

Pruning Too Much

It’s possible to overdo the pruning process. “If a gardener removes a lot of foliage from a plant, it increases the chances of the fruits getting sunscald,” says Mulvihill. “This is a form of sunburn that damages them.”