Tomato Pruning Tips

Tomatoes are probably the most popular plants in the home vegetable garden. They are tasty and boast a variety of uses from pastas, 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 branches 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 access to 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.

A little background on tomatoes is in order. All tomatoes fall largely into two categories, determinate or indeterminate as it relates to their 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. 

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. 

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 main central vine. If a sucker is left unpruned, it may eventually compete with the main stem and ultimately reduce fruit production.

Determinate tomatoes need no pruning other than the removal of all suckers below the first set of flowers. Additional pruning will not affect fruit size or plant vigor. However, if pruning is done anywhere above the first flower cluster, the tomato harvest will be reduced. 

Following is a step-by-step tomato pruning guide.

Step 1: Remove dead or diseased branches. When pruning, 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.

As long as your tomatoes have strong main stems, it’s fine to leave a few suckers on the plant. The general recommendation is to leave two or three suckers to improve yield, but not to let every sucker grow. 

If you are concerned about your indeterminate tomato growing tall and cumbersome, you might try this: once the plant has reached an ideal height (such as the top of your support cage or stake), simply pinch out the main terminal (top) bud on each main branch. This will help keep the plant at that height. Of course, your harvest will be reduced accordingly. 

Tomato pruning is more trial and error than precision, so look at it as an experiment. When you first start pruning, do less rather than more. If you grow the same varieties year after year, you’ll get a feel for how they respond to pruning. 

Tim Lewis is a Georgia Green Industry Association Certified Plant Professional, gardening writer, and former Perry High School horticulture instructor. He can be reached at (478) 954-1507 or timlewis1@windstream.net.