Should I defoliate my tomato plants to increase fruit production?
Do you like training your plants and checking on them on a daily basis? If so, then you may be a natural tomato pruner. Some gardeners utilize tomato plant pruning to keep plants clean, regulate fruit size, and even expedite ripening. Only indeterminate cultivars, which produce new leaves and blooms continually throughout the growing season, should be pruned. If you prune determinate varieties, you may reduce the harvest. (Looking for indeterminate varieties to plant? Try our Tomato Selector.) These are several reasons why you should prune your tomatoes.
Improved airflow and less disease
Pruned plants are less thick because they have fewer leaves, enabling more air to pass through them. The leaves dry faster after a rain, so they are less susceptible to the diseases that need prolonged moisture to develop — something that can be very helpful in wet climates. Also, fewer leaves make it simpler to detect insect pests that would otherwise be covered by a dense canopy.
Pruning at the correct moment puts energy into the creation and ripening of fruit rather than the production of new leaves. Overall, a trimmed plant will produce fewer fruits, but they will be larger. And, since pruned plants can be put a bit closer together in the ground because the growth is so vertical, you’ll have room for additional plants to make up the difference in harvest numbers.
When a plant’s leaves and physiology have fewer fruits to tend to, the fruit ripens more quickly. This can really help in short season climates, where getting a tomato harvest is often a race against time, thanks to early fall frosts.
How to prune tomatoes (indeterminate varieties only!)
Tomatoes should be pruned throughout the season. Here’s what to do and when:
- Remove the lower leaves when planting so you can bury plants deeply into the soil. Follow the instructions on the packaging before planting a Bonnie plant.
- Remove any blooms existing at planting time (even if they were there when you purchased the plant) so that energy is directed on foliage development rather than fruiting at this early stage.
- Remove blossoms until the plants are 12 to 18 inches tall, allowing the plants to devote more energy to the roots.
- Remove any leafy suckers under the first fruit cluster to avoid slowing fruit growth. Suckers are the little shoots that emerge when the leaf stem connects to the main growing stem (called an axil). Many gardeners in northern areas go even farther, eradicating all suckers as they emerge. In warmer zones, though, experts often recommend practicing what’s known as Missouri pruning, where you pinch off the leaflets on the end of each sucker, leaving only the two base leaflets in place. When these leaves grow in size, they shade the fruit and protect it from sunscald. Try to remove suckers when they’re small enough to pinch with your fingers, so you don’t leave a gaping wound on the stem. If you must cut them, make a clean cut as near to the main stem as possible without injuring stem tissue using a sharp knife or pruner blade.
- Tomato plants are often still filled with fruit as the growth season comes to an end. Remove the developing tip of each main stem approximately four weeks before the first projected autumn frost to accelerate ripening late in the season. This method of trimming, known as “topping,” forces the plant to cease blooming and producing new fruit, instead directing all glucose to the current fruit. This allows the fruit to mature quicker, and it increases the likelihood that green tomatoes picked before frost will ripen when brought inside. It will be difficult to force yourself to do this, but it will be worthwhile if you want ripe tomatoes! Of course, if you want your tomatoes to stay green for frying and jelly, you may omit this step.
What if I already have big plants in the garden?
– Growing and pruning to a vertical stake may be not be an option for this year, but both determinate and indeterminate varieties benefit from removing the lower leaves to keep soil-borne diseases from splashing up onto the foliage. (You may have seen leaf spots and blotches on the lower leaves already.) Remove any leaves that are in contact with the soil and continue trimming up to a foot from the ground. Several tomato diseases, such as septoria and early blight, may be found in soils, particularly in the Northeast, Mid-Atlantic, and upper Midwest. As the plants get bigger, you may continue to remove lower leaves up to 18 inches from the ground to help prevent disease spread. To minimize disease transmission, work while the leaves are dry.
– Remove some leaves from the center of cage-supported plants to enhance ventilation, which may help prevent and/or reduce disease outbreaks. According to research, the leaves closest to a fruit cluster are the ones that transfer sugar to that fruit, therefore while thinning, avoid removing leaves just above and below the cluster. As a result, the leaves above may shade the maturing fruit while the leaves below can deliver sugars to it.
Next time you plant
Pruning works best on plants that are robust and aggressively developing. Start with young tomato plants from Bonnie Plants® (look for the logo!) to offer your tomato plants the greatest chance for outstanding development. Finally, put them in well-draining, nutrient-rich soil and fertilize them on a regular basis. Miracle-Gro® Performance Organics® All Purpose In-Ground Soil (for garden beds) and Miracle-Gro® Performance Organics® All Purpose Container Mix (for pots) are both enriched with aged compost and will provide an excellent environment for roots. Use one of these with Miracle-Gro® Performance Organics® All Purpose Plant Nutrition Granules, a continuous-release plant food that nourishes both your plants and the beneficial bacteria in the soil. Examine the label to determine how much and how often to fertilize.