Written By Ashleigh Smith

Tomatoes are one of the most popular plants in the home vegetable garden. They are tasty and boast a variety of uses from pasts, sauces, salsas, and so much more! Boost your tomato yields by properly pruning your plants for greater health and fruit production.

Why Prune Tomato Plants?

As tomatoes grow, they continue to develop branches, leaves, and fruit from the main stem. However, some of these branches develop quick and vigorous foliage growth over fruit production. These are called suckers. If suckers, or regular branches for that matter grow too densely, you may experience greater pest and disease problems relating to poor air circulation and light access. Pruning can help to open up the plant to greater light access and improve air circulation for healthier growth, larger, and higher fruit quality over excessive foliage growth. Regular pruning can also keep your harvest visible and within reach.

Determinate vs. Indeterminate Tomatoes

All tomatoes fall largely into two categories, determinate or indeterminate growth habits. Determinate tomatoes tend to be shorter and bushier, with a limited height range. They also set all of their fruit within a limited time frame. While they may need some light pruning from time to time, this should be limited to removing dead or damaged leaves.

Indeterminate types, on the other hand, will continue to produce fruit throughout the summer season. They will also continue to grow vertically with a vining habit that requires support for healthy growth. Indeterminate tomatoes require greater care as they are more likely to need ongoing pruning throughout the season to remove dead or damaged leaves, excessive growth, and sucker branches. However, it comes with great rewards of a plentiful harvest.

When and How to Start Pruning Tomatoes

Best Time to Prune Tomato Plants

The best time to start pruning tomatoes is when they are young, around a foot tall, and have several sets of leaves. This will allow the plant to continue gathering the light it needs with the remaining leaves. Remember to avoid pruning during extreme heat or just before a rainstorm. Excessive heat can cause the plant to be stressed as it works to retain the needed water in its stems and leaves. Removing its reserves and causing small injuries at the cutting sites can cause it to become further stressed. Pruning just before rain can also leave the cutting sites open to diseases associated with increased humidity.

Signs Your Tomato Plant Is Ready for Pruning

You will know your plant is ready to be pruned by the distinct growth habit of sucker branches and the change in leaf color and form. Yellowing, drying, and crinkling leaves should be removed to preserve the health of the plant. These will typically form on the lower branches. If left unpruned, they will likely fall anyway. Removing struggling leaves and branches allows the plant to divert nutrients and growth to healthier and more productive parts of the plant, ultimately reducing the stress it experiences.

Suckers are the quick-to-grow branches that form at the leaf axils. This is where the branches extend from the main vine. Regular branches will form horizontally away from the stem. Suckers form at a 45 degree angle and extend upwards. When growing tomatoes, it is best to maintain one central vine. If a sucker is left unpruned, it may eventually compete with the main stem and ultimately reduce fruit production.

Basic Pruning Tools for Beginners

Always use clean tools. If you notice a plant carries a disease or virus, be sure to clean your tools between plants, even between cuts.

Step-by-Step Tomato Pruning Guide

Step 1: Remove Dead or Diseased Branches

When pruning, regardless of the plant, removing the dead or diseased portions is the most important place to start. This will help your plants divert their energy to new growth and fruit production.

Step 2: Remove Suckers

Suckers will form along the central vine in the “V” between the main stem and leaves/branches. It is best to catch these guys when they are young and short. When left to grow, suckers can quickly increase by several inches, eventually competing with the central stem. This should be avoided as suckers will reduce your harvesting yields.

Step 3: Remove the Lower Leaves

Once the dead and diseased branches and suckers have been removed, you may consider removing any branches below developing fruit. This is optional, but it may improve air circulation and promote fruit ripening.

Common Pruning Mistakes (and How to Avoid Them)

It is important to regularly check your plants and maintain them as you go. Waiting and pruning a lot all at once can lead to over-pruning. Avoid removing more than a third of the plant at a time. This rule applies to any pruning, be it of tomatoes, trees, or shrubs.

If your plants begin to develop robust growth, you may be tempted to top them early in the season. Don’t! Indeterminate tomato plants shouldn’t be topped (pruning the top of the central vine) until late in the season. Topping can help the fruit already on the plant ripen as the end of the season approaches. If you top them too early, it will stop the development of additional upward growth and therefore reduce your potential harvesting yields.

Bonus Tips for Healthier Tomato Plants

• Supporting with Cages or Stakes - Providing vertical growing support isn't just for looks. Cages and stakes help prevent stems from snapping under the weight of developing fruit. They also help maintain good airflow for better overal health.
• Companion Planting for Pest Control - Pests will appear in every garden, but companion plants can help control the level of damage you are likely to see. Add companion plants to your garden to deter pests and attract beneficial insects. As an added layer of protection, we also recommend utilizing Neem Oil. An organic solution to control pests at any stage.
• Feeding and Watering After Pruning - After you prune, feed your plants to help them recover and develop new growth. Be careful not to use a fertilizer heavy in Nitrogen as this will cause your plants to develop foliage over fruit. When looking at fertilizers you can observe 3 numbers. These represent the amount of nitrogen, phosphorus, and potassium, in this order. Select one with a high value for phosphorus, a moderate number for potassium, with the nitrogen value being the lowest.

As you take on this gardening season, we hope you will gather your best harvest yet! Keep your tomato plants happy and healthy by regularly checking them for pests, suckers, and other damage. Don’t be afraid to give them a little haircut every now and then to support upward growth and greater fruit production. Happy Harvesting!