Summer is almost here, which means that your tomato plants are probably due for their first pruning. As May turns into June and temperatures climb, newly transplanted tomatoes start to make big leaps in terms of growth. They relish the longer days and warmer nights of late spring and early summer.

But as tomatoes grow, they can start to get a little bit out of control. They grow quickly and put out lots of suckers that direct energy away from fruit production. When this begins, it’s time to start pruning tomato plants. Making some simple cuts now will keep your tomatoes tidy – which helps prevent disease – and it will also increase your yields.

Before you pick up the pruners, there are a few basics you need to learn to ensure you make the right cuts. Not all tomatoes require pruning. Plus, cutting in the wrong spot can actually ruin your chances of a big harvest. Here’s how to start pruning tomatoes and why right now is the most important time to make the cut.

Do All Tomatoes Require Pruning?

Not all tomatoes are created equal. There are two main types of tomatoes: determinate and indeterminate. Determinate tomatoes are bush-type tomatoes, which means they stop growing at a certain height. They are much shorter and more compact than indeterminate varieties and they don’t require pruning.

Indeterminate tomatoes can reach up to 6 feet (2 m) or higher, if you let them keep growing. They put out lots of suckers that divert energy and nutrients away from fruit production. These vining types of tomatoes produce best when you prune them. This directs the plant’s resources towards growing lots of big, juicy tomatoes. Pruning also makes fruit ripen faster, especially at the end of the season.

Benefits of Pruning Tomatoes

A bigger harvest isn’t the only benefit of pruning indeterminate tomatoes. Making smart cuts can also keep plants healthier.

Tomatoes can quickly produce lots of branches full of leaves that become crowded. Pruning away suckers and unnecessary branches improves airflow, which helps prevent common tomato diseases.

Keeping plants tidy by pruning them regularly also makes it easier to spot common tomato pests. There are less leaves where hungry tomato hornworms and annoying aphids can hide.

Best Time to Start Pruning Tomatoes

The best time to start pruning tomatoes is once plants are at least 12 inches (30 cm) tall. Depending on where you live and when you started your tomatoes, the exact date will vary. But many gardeners’ tomatoes pass this threshold in early June. So now is the perfect time to pick up your pruners – our team of gardening experts swear by these Felco pruners – or use your fingers to start pinching off suckers.

New sprouts show up fast, so you need to continue pruning away tomato suckers every week or two throughout the rest of the growing season. Luckily, pruning opens up the structure of your tomato plants and makes it easier to see suckers as they emerge. Snap or cut off suckers before they get too big. It’s best to remove them when they’re under 2 inches (5 cm) long. This handy thumb knife from Amazon makes plucking suckers easy – and kind of fun!

Prune tomato plants in the morning, but don’t make any cuts if plants are wet. This can invite disease. If your plants show any signs of disease, be sure to sterilize your pruners between each plant or else you risk spreading the problem to other plants.

Even if your tomato plants aren’t 12 inches (30 cm) tall yet, there may still be some pruning you need to do. Tomatoes that are producing flowers, but are under the 12-inch (30 cm) threshold require pruning as well.

Pluck off any tomato flowers that appear on plants under 1 foot (30 cm) tall. If you leave them, they may develop into normal fruits. But at this point in the growth cycle, letting a small plant bloom and produce a fruit is only going to sap your tomato of energy it will need later. Wait until your tomatoes hit the 1-foot (30 cm) mark before allowing flowers to progress into fruit.

Don’t Make This Pruning Mistake

Pruning tomatoes is quick, simple, and – honestly – kind of fun to do. It’s a great time to check on your plants’ health, look for any unwanted bugs, and train your tomatoes to grow big and strong. But it’s also easy to get carried away when pruning and end up making a cut you shouldn’t have. And there’s one tomato pruning mistake in particular that can ruin your harvest for the rest of the summer.

Do not cut off the top of the main stem. Only prune off the suckers that emerge in the joints between the side branches and the main stem. If you accidentally top your tomato plant at this point in the season, you will severely cut down on your yield of fruit for the rest of the summer. All of the other branches come off of this stem and that’s where your tomato fruits emerge and develop.

However, if you do accidentally top your tomato, you can allow a couple of suckers to develop and turn those into new main stems. They probably won’t be as strong as the original main stem, but they will still produce plenty of fruit.

Tomato Pruning Essentials