Indeterminate tomato varieties benefit from stringing, a vertical support method. This technique involves suspending the main vine vertically using twine anchored to an overhead structure, allowing the plant to grow tall without collapsing under its own weight or the load of its fruit. Commercial growers and home gardeners use this system to maximize the potential of vining tomatoes and ensure a lengthy, productive harvest season.
Why Employ Vertical Support
Indeterminate tomato plants are true vines, capable of growing over ten feet tall, making a robust vertical support system necessary. Keeping the foliage and developing fruit off the ground is a significant benefit, as it sharply reduces the plant’s exposure to soilborne pathogens like early blight and late blight. Fungal spores often splash onto lower leaves from the soil during watering or rain, but stringing minimizes this contact.
Vertical training also improves air circulation around the plant canopy, helping leaves dry quickly and inhibiting the spread of fungal diseases. The vertical orientation efficiently utilizes garden space, allowing gardeners to plant more closely together while ensuring adequate light penetration. Keeping the fruit suspended also protects it from ground pests and prevents fruit rot that occurs when tomatoes sit in damp soil.
Gathering Materials and Preparation
The overhead stringing method requires three main components: a durable overhead support structure, strong twine, and a means to anchor the string at the base of the plant. The overhead support must be strong enough to bear the considerable weight of fully grown plants laden with fruit. This structure is often a high-tensile wire or a sturdy beam, such as galvanized pipe or wood posts, set at least six to eight feet above the ground.
The twine should be a soft, yet strong, material like jute, sisal, or synthetic baling twine, as it must not cut into the delicate tomato stem. Biodegradable options are often preferred for easy cleanup at the end of the season. The string is tied to the overhead support and hangs down to the base of the plant, where it is secured with a garden staple, a small ground anchor, or looped loosely around the main stem. Stringing should begin once the plant is established and about 12 to 18 inches tall, ensuring the support is in place before the stem becomes too heavy or fragile.
Step-by-Step Guide to Stringing
The stringing process begins with anchoring the twine at the base of the plant, ensuring the string runs vertically from the ground to the overhead support wire. Secure the string by tying it loosely around the main stem just below a lower leaf or by anchoring it into the soil near the plant’s base with a landscape staple. The goal is a secure anchor point that will not girdle or damage the stem as the plant grows.
Next, the twine must be secured to the overhead structure, such as a sturdy wire run between posts or a greenhouse beam. Tie the top of the string using a knot that can be adjusted or released later, such as a slip knot or a simple loop. Ensure the string is taut but not overly tight; the tension is necessary to keep the line straight and capable of supporting the vine’s weight.
Once the string is secured top and bottom, the main stem of the tomato plant must be gently trained to the twine. Begin the wrapping process by twisting the main stem around the string in a consistent direction, either clockwise or counter-clockwise. This twisting motion allows the plant to use the string as its primary support.
This support is more secure than simply tying the plant to the string. Take care to avoid snapping the main stem during this initial wrap, especially near the growing tip. This process will be repeated weekly as the plant grows taller.
Ongoing Management and Pruning
Stringing necessitates a specific pruning regimen known as single-stem training to maintain the system’s efficiency and prevent the plant from becoming a tangled mass. This method involves removing all “suckers,” which are the lateral shoots that develop in the leaf axils. By removing these suckers, the plant’s energy is redirected into vertical growth and fruit production along the single main stem.
Suckers should be pinched off when they are still very small, ideally less than two inches long, to avoid creating large wounds that could invite disease. This removal is a continuous task, typically performed during a weekly inspection. As the main stem grows, it must be gently twisted around the vertical string every week or so to keep the vine upright. Additionally, removing the lowest leaves as the plant matures improves air circulation and reduces the pathway for soilborne diseases to climb the plant.