Pruning a tomato plant can help plants direct more energy to flowering and fruiting, reduce disease issues by allowing more light penetration and air circulation, and help control the size, which is particularly helpful in small garden spaces.
Pruning Suckers | Pruning Lower Leaves | Topping | More Information
Pruning Suckers
Suckers are small stems that grow between the main stem and the leaf axil. Pruning suckers is a helpful practice. Suckers are primarily vegetative (and do not produce much, if any, fruit). Leaving them on means the plant devotes a lot of energy to growing suckers instead of producing more fruit. Removing suckers can also open the canopy, allowing better air circulation and reducing the potential for foliar diseases.
How to Remove Suckers
To remove suckers, identify the main stem. Follow it up from the base of the plant. At each junction (node) grows a compound leaf. In between those two structures, you can find a new stem developing. That stem is the sucker. Simply snap off with your fingers or prune out with sharp pruners the sucker when it is small (less than a few inches long).
For determinate tomatoes, remove suckers up to the first cluster of flowers. There is no need to remove suckers above that point on the main stem. Yields do not increase by removing suckers beyond the first flower cluster on determinate tomatoes.
For indeterminate tomatoes, continue to remove suckers as they form all along the main stem throughout the growing season.
Helpful Tips
It is not necessary to remove every sucker on the main stem, especially if it leaves the leaf canopy very open. When there is not enough foliage, tomatoes can be exposed to bright sunlight and develop sunburn or sunscald, which can damage the fruit.
Disinfect your hands and pruning equipment, especially if you smoke or use tobacco. Clean your hands or tools between plants, or every few plants, to help prevent the accidental spread of diseases. Learn more in this article: How do I sanitize my pruning shears?
Snap or cut the sucker cleanly from the plant. Do not leave behind a jagged wound.
Removing Lower Leaves
Pruning the lower leaves of tomato plants helps improve air circulation around the stem, reduces soil-borne diseases such as early blight and Septoria leaf spot, and can make watering and harvesting easier.
How to Prune Leaves
When pruning, remove the leaves and side shoots from the bottom 6–12 inches of the plant, especially any foliage that touches or is close to the soil. Use clean, sharp pruners and make cuts close to the main stem without damaging it.
For best results, prune on a dry day so wounds heal quickly, avoid removing more than one-third of the plant's foliage at a time, and mulch around the base to further reduce soil splash that can spread disease.
Regularly inspecting and removing yellowing or diseased leaves will help keep plants healthy and productive throughout the season.
Topping
Topping a tomato plant can be a useful practice for indeterminate varieties when the goal is to encourage fruit ripening at the end of the growing season rather than additional vegetative growth. By removing the growing tip of the main stem, the plant directs more energy into developing and maturing existing fruit rather than producing new leaves, flowers, and stems. This practice is not recommended for determinate tomato types as they will grow to a predictable size and produce all of their fruit at once. Topping them at any stage will significantly reduce yields.
When To Top Tomato Plants
Topping is best done in late summer, about four to six weeks before the average first fall frost date. It is not recommended early in the growing season, especially if plants have not yet produced flowers and fruit or have just begun to do so. When done too early, topping can reduce overall plant growth and yields.
How to Top Tomato Plants
To top a tomato plant, use clean, sharp pruners to cut the main stem just above a leaf or fruit cluster. For best results, avoid topping plants that are already stressed by drought, disease, or nutrient deficiencies. Make cuts during dry weather to reduce the risk of disease, and continue to provide consistent moisture and proper nutrition.
Topping is not necessary for all tomato plants, but it can be an effective tool for gardeners who want to improve fruit ripening and maximize harvest quality as the growing season comes to an end. Another way to promote better late-season ripening is by removing flowers as they appear, starting about 4 weeks before the first fall frost.
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