Beefsteak tomatoes are a category of Solanum lycopersicum varieties known for producing exceptionally large, meaty fruit, often weighing a pound or more. Most of these varieties exhibit an indeterminate growth habit, meaning the plant will continuously grow and produce flowers and fruit until frost kills it. Pruning is necessary for these vining plants, transforming their natural, sprawling growth into a productive structure. This intervention maximizes the size and quality of the final harvest by focusing the plant’s energy on developing large tomatoes.
The Purpose of Pruning Beefsteak Tomatoes
Pruning serves a dual function by controlling the plant’s energy distribution and enhancing its overall health. Unpruned indeterminate tomato plants direct resources into vegetative growth, producing numerous leaves and stems. Removing this excess growth redirects the plant’s metabolic energy, including sugars and nutrients, toward the developing fruit.
This redirection results in fewer, but significantly larger, tomatoes, which is the desired outcome for beefsteak varieties. Pruning also opens up the canopy, allowing for improved air circulation around the stems and leaves. Better airflow helps the foliage dry quickly after watering or rain, preventing common fungal diseases like early blight.
Identifying and Removing Suckers
The most important pruning technique involves removing “suckers,” which are new lateral shoots that emerge in the crotch between the main stem and a leaf branch. If left to grow, these suckers develop into full, fruit-producing stems, creating a bushier plant. This increased density divides the plant’s energy among too many fruit sites, resulting in smaller tomatoes.
The key to effective sucker removal is vigilance and timing, ideally checking the plants every three to five days. When suckers are very small, typically less than four inches long, they can be easily pinched off with your thumb and forefinger. This method creates a small, clean wound that heals quickly.
For suckers thicker than a pencil, using clean pruning shears or a sharp knife is recommended to avoid tearing the main stem. This cutting technique minimizes damage, as snapping off a thick sucker can leave a large, jagged wound susceptible to disease. The goal is to manage the plant to a single main stem, sometimes called the leader, or occasionally to a double-stem system for a slightly larger yield of substantial fruit.
Always leave the main stem and the leaf branches that emerge directly from it, only removing the new growth from the joint between them. Carefully distinguish between a sucker and a cluster of flowers or a fruit truss, as flower clusters emerge directly from the main stem, not from the leaf axil. Removing the wrong growth will eliminate a future harvest.
Managing Foliage and Lower Branches
Pruning includes the strategic removal of certain leaves and lower branches to maintain plant vigor and prevent disease. The lower branches are the first to yellow as the plant matures. These lowest leaves are vulnerable to soil-borne pathogens, which can splash onto the foliage during watering or rain.
To combat this, remove all leaves and branches up to 12 to 18 inches from the soil line, especially once the plant has set its first fruit clusters. This creates a clean zone between the soil and the plant’s main structure, reducing the risk of fungal spores spreading. Additionally, promptly clip off any leaves higher up that appear yellowed, damaged, or diseased.
When removing foliage, use clean tools to prevent the transmission of pathogens between plants or plant parts. Wiping shears with a household disinfectant, such as rubbing alcohol, between cuts is an effective sanitation practice. Removing select interior leaves also improves light penetration and air circulation within the canopy, discouraging humid conditions that favor disease development.
Post-Pruning Care and Support
The intentional reduction of foliage means the plant’s remaining structure must be adequately supported, especially as the heavy beefsteak fruit develops. Sturdy staking, caging, or a trellis system is required to bear the weight of the fruit and the tall vine. Installing a strong support, such as an eight-foot stake driven deep into the ground, at the time of planting is easier than adding it later.
The main stem should be loosely tied to the support using soft material, like cloth strips or soft twine, to prevent the tie from cutting into the stem as it grows. Tying should occur just beneath a leaf branch or fruit cluster for maximum support.
Pruning should always be done when the foliage is dry, never when it is wet, to minimize disease entry points. After pruning, avoid watering the plant overhead, as the fresh wounds need to dry quickly to seal themselves against potential infection.
Avoid removing more than one-third of the plant’s total foliage at one time to prevent severe shock that can temporarily stunt growth. Later in the season, about one month before the first expected frost, the growing tip of the main stem can be “topped.” This forces the plant’s remaining energy into ripening existing fruit rather than producing new growth that will not mature.