When Should You Prune Your Tomato Plants This Season?

Are you unsure when you should start pruning your tomato plants this season? Regular pruning is an essential part of tomato plant maintenance, so it's important to do it regularly. In this article, gardening expert and farm owner Jenna Rich details when you should be pruning your tomato plants!

A gardener wearing black latex gloves pruning tomato plants that are on the vine, in a greenhouse. The tomatoes are green and not yet ripe.

Nothing says summer quite like fresh, juicy tomatoes! Especially if you wait all winter long, as I do on my New Hampshire vegetable farm. Homegrown garden tomatoes have more flavor than store bought varieties, making them an easy pick for gardeners who want to grow vegetables.

Tomatoes are a favorite annual vegetable among gardeners around the globe, but learning to care for them can be tricky. Pruning is an important step in tomato plant maintenance. But many questions arise when pruning come up. Some of the most common are “when should I start pruning tomato plants?”, “where do you cut the stems?”, and “what are the best tools to use?”

You’ll want to start pruning early and stay on it all season long in order to keep your tomato plants healthy and productive. Here’s everything you need to know about when to prune your tomato plants, with a quick overview on how it’s done. Ready to learn more? Let’s dig in!

The Short Answer

Tomato pruning should begin actively at the time of planting and then continue weekly or biweekly throughout the entire growing season. The frequency of when to prune tomato plants depends on the variety, growth of suckers, and your trellising system.

The Long Answer

Gardener using hands and pruning shears with red rubber grips to snip at branches growing low on a plant. The plant is in a garden with soil and a few other plants.
Tomato plants should be pruned from the time of transplanting and throughout its life.

Before transplanting plants, they should be pruned to remove low-hanging leaves, especially any that are yellowing. After any initial transplant shock a few weeks later, check your plants again and look for any small suckers.

The smaller the sucker, the smaller the wound to the plant. So it’s important to catch them early. Be sure to get your snips as close to the plant as possible, producing a smooth wound that is flush with the stem. Once suckers are larger than a pencil, use snips to remove any possibility of damage that might lead to disease.

At this time, you really want the plants to focus their energy into the root system and forming the main stem. Take care not to cause too much stress by over-pruning.

Most gardeners will then begin pruning weekly or biweekly, depending on variety, schedule, and tomato trellis system. Some gardeners “top” their plants when nearing the end of their season.

The bottom ⅓ of the plant should be kept clear of leaves and debris. This will give them the best chance at living disease free and thriving. Just be sure to leave an ample number of leaves as this is how the young plant takes in the sun.

Simply put, if tomato plants are not pruned, they will produce lots of flowers, suckers and foliage. This results in over-crowding, a lack of resources, and inconsistently shaped and sized fruits.

Required Pruning Tools

Close up of gardener holding pruners with orange handles about to snip away at a plant in a greenhouse. The plant is staked with string and has small yellow flowers blooming on some of the vines.
Pruning shears should be sharp and sanitized with alcohol or a diluted bleach solution.

There are a number of specialized pruning tools that can be used to remove tomato plant growth. They come in different styles and sizes. Choose whichever shears best suits you! Just be sure that they are sanitized and sharpened. This is very important because when you prune a plant, you are opening it up to disease.

Here are the required tools you’ll need to start pruning:

  • Pruning shears
  • A trellis system of some sort
  • A bucket for clippings
  • A notepad for taking notes if desired

Pruning Throughout the Season

Unripe green tomato fruits being held by a gardener's hand called a truss, with several round green fruits ripening on the vine. There are more fruits and the wall of the greenhouse in the blurred background.
Once they start to grow in bunches, the leaves can be removed each week to prevent further growth.

Once your tomatoes have been ripening for some time, you should begin to remove the empty clusters, called trusses, and any leaves below the empty truss. Do not remove too many of the leaves before the tomatoes have been harvested as this can lead to sunscald on the fruit.

Basically, once the plants are cranking out tomatoes, you can remove 2-3 leaves or more per week. Removing the leaves below a newly ripening cluster will reallocate energy to ripening these fruits. A general rule of thumb is that the bottom ⅓ of your plant should be clear of leaves and empty trusses.

Pro Tip

Be sure to keep your clippings in a bucket and add to a compost or burn pile as these leaves could be holding on to disease-like blight that can be splashed up onto lower leaves after rainfall. Leaving them in your tomato area could allow the disease to spread.

Later in the season, some gardeners will remove the growing tip of their plants which is referred to as “topping.” This forces sugars into the fruit already on the plant and stops production of any new growth, ensuring the fruit ripens before the first frost date, and allowing you to take full advantage of the remainder of the season!

Pruning Determinate vs. Indeterminate Tomatoes

Row of staked plants growing in containers all in a row in a greenhouse. There are ripe red and unripe green round fruits blooming from the vines of the plant.
Only indeterminate tomatoes will need to be pruned.

There are many varieties of tomatoes to choose from when planning your garden. The two types are determinate and indeterminate varieties (which simply has to do with their growing habits), cherries, heirlooms, classic reds, Roma-type, cocktail, and so many more.

They all grow slightly differently and have different needs. Be sure to know how your plants will grow in order to determine how best to treat them.

Determinate Tomatoes

Often referred to as “bush tomatoes” because they only grow to be 4-5 feet tall, these plants basically come on all around the same time, usually for about a two-week period. You would want to grow this type if you want large quantities to be ready all together for making sauces, salsa, etc.

This type of plant does not necessarily require pruning as they stop growing when they stop fruiting. However, caging or staking is still recommended because the weight of the fruit could cause them to topple over if they are not.

Indeterminate Tomatoes

These plants are sometimes called “vining tomatoes” as they will continue to vine up a trellis for the whole season and will set fruit as long as they can.

It is likely that the varieties you see at farmers’ markets will be indeterminate varieties as they will allow farmers to have an extended harvest time for tomato sales.

These will easily grow to over 12-14 feet if given a proper trellis. If not pruned, suckers and foliage will take over, so maintaining this type of plant is vital for success.

Identifying a Sucker

Close up of a small green leafed sucker growing in between two mature green branches called an axil. These plants are growing inside a greenhouse in the blurred background.
Suckers are small growths that sprout from in between existing branches.

A sucker is a side shoot that tomato plants send out. They appear between the main stem and the leaves, on an upward diagonal in a space known as the “axil.” You should identify them when they are small and snip them off early.

If not, they will grow into new stems and produce flowers and fruit. This creates a mess and lots of competition throughout the plants.

Pro Tip

If you are using a double leader system, you will want to choose a strong sucker early in the season to become your second leader and use trellising to train it up. It is sometimes recommended to leave a few suckers on early in the season until you are certain the main stem will survive. If it does not, you will then have other options for continued growth.

The Importance of Removing Suckers and Leaves

Close up of a gardener snipping a very young and small sucker off a plant. They are using small red pruners with the greenhouse, and the background past the tomato pruning is out of focus.
Removing new growth allows the plant to redirect energy into its fruit and existing growth.

Tomato plants send out suckers because their ultimate goal is to create lots of fruit. This is so they can spread their seeds. Keeping them on will get you more fruit, so snipping them off may seem counterintuitive.

However, you want the plant to focus its energy on the one main stem (or two if you are using a double leader system) so that it can get big and strong.

Pruning off the suckers will also get you fruit sooner in the season. This is because the main fruit are not competing against its sucker sisters for nutrients, sun, and other resources.

Pruning leaves allows for quality air control, sends energy to ripening fruit, removes potential disease, and gives tobacco and tomato hornworms fewer places to hide under and snack on.

What to do With the Cuttings

If you’re like me and are growing lots of tomatoes, your main task is completing the weekly pruning and then getting the debris into the burn pile. But you might have the capacity to try your hand at potting them up, or propagating them.

Each sucker has the potential to become a clone of the main plant. Bury it deep in a 4-8 inch pot and keep moist. Roots should form within a few weeks. This precious plant would make a great housewarming gift for a friend or new neighbor.

Frequently Asked Questions

What if I mistakenly cut off the growing tip?

If it’s early enough in the season, you can allow a sucker at a similar height to grow large and become the leader. Just be sure to adjust your trellis to make this new leader grow up instead of out. Easy! If it’s later in the season and nearing frost, the plant will just focus its energy on ripening any remaining fruit.

Why are my tomatoes getting sunscald?

You may have overpruned. Be sure to wait to cut lower leaves off until the tomatoes below them have ripened and harvested. Otherwise, they are being exposed suddenly to direct sun when they were previously protected by the leaf coverage.

Why does my heirloom tomato have suckers in strange places?

You may have missed a sucker and it has gotten out of control. Heirloom suckers can get funky and be tricky to spot. Just follow the branch up to the main stem paying attention to its growing habit. It may have flowers, but don’t let that confuse you. Small suckers become big suckers so get rid of them as soon as possible.

Suckers can get their own suckers too! Remember, they are trying to reproduce and will do so however they can.

What is a double leader system?

Some growers choose a strong, low-hanging sucker and avoid cutting it so that it will grow into a second stem, giving them two strong leaders. Using a trellis system, you train this sucker up and allow it to fruit.

This system allows you to get the same amount of tomatoes with fewer plants! Just be sure to give your plants ample growing space and airflow. It is recommended to give tomatoes 12-36 inches for single leaders so be sure to adjust if you try this method.

Final Thoughts

Growing tomatoes is a fun summer activity with great rewards. By pruning your tomatoes properly, you’ll extend your season, keep disease pressure down, and give you lots of delicious fruit to enjoy fresh or preserve for winter consumption. Don’t be afraid to give it a shot!

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