Tomato Plants: To Prune or Not to Prune?

tomato plants with growth

The Spruce / Autumn Wood

Pruning tomato plants is somewhat of a hot topic amongst tomato growers. Some swear that you must prune, and others are adamantly against pruning. As with most things in life, there really isn't one best answer. It depends both on the conditions in your garden and your goals.

Busting the Pruning Myths

You'll hear plenty of explanations for why you should prune tomato plants, including:

  • You'll get more tomatoes.
  • You'll get bigger tomatoes.
  • Your plants will get more airflow, benefiting the plants.
  • You'll save space in the garden.

Of these four reasons, the first two are not necessarily applicable to all tomato plants, but the latter two bear some validity. If you have fungal issues in your garden, airflow definitely should be considered, and you may want to prune your tomato plants. However, if your plants are not regularly bothered by leaf spots or other fungal issues, you probably don't need to worry about pruning.

Another way to be sure you're keeping your plants safe from fungal issues is to avoid wetting the foliage when watering and to try to water early in the day, so any moisture on the plant can dry up before nightfall. Also, try to avoid working near your plants when they're wet, as this can spread fungal issues, and clean your pruners regularly.

Additionally, if your tomato plants are lying on the ground, you might want to prune them. When leaves are forced into permanent shade, such as when the bushy plants are on the ground, the amount of sugar they produce is reduced. Eventually, the leaf will yellow and drop off. However, instead of pruning, you can also stake your tomato plant to keep the leaves off the ground.

One Reason to Prune

Really, it's that final reason—space-saving—that is the main reason you may want to prune your tomato plants. Tomatoes, especially indeterminate varieties, can become giant, sprawling plants by the end of the season. If your gardening space is limited, or, like many gardeners, you're trying to fit more plants into a small space, you'll want to prune your tomato plants regularly and keep them staked or caged. This will prevent your plants from getting too large and bushy. However, indeterminate plants will still keep growing taller, and you'll keep getting fruit as long as the plant is growing.

Reasons Not to Prune Tomato Plants

The reason for not pruning is best explained by Dr. Carolyn Male, a professor of microbiology and noted gardener, in her book, "100 Heirloom Tomatoes." "I'm firmly against pruning," she wrote. "Plants need to photosynthesize to produce energy for root, leaf, and fruit growth. Therefore, by allowing all of the plant's foliage to thrive, the plant is better able to photosynthesize."

As for pruned plants producing larger fruit, that's also fairly inaccurate. As Male mentions, the way you get larger fruit is to remove all but one or two of the small fruits per stem. The remaining fruits, because all of the plant's energy is going to them, will grow larger than they would have if you'd left all of the fruits.