Growing tomatoes vertically on a trellis is a highly effective gardening technique that significantly improves plant health and overall yield. This method, often called vertical gardening, maximizes space, which is especially beneficial in smaller gardens or raised beds. Keeping the foliage and fruit off the ground reduces exposure to soil-borne pathogens, leading to healthier plants and cleaner produce. Improved air circulation around the vines also helps the leaves dry faster after rain or watering, which drastically lowers the risk of fungal diseases like blight. Trellising ultimately makes the fruit easier to access for harvesting, while also increasing the amount of sunlight that reaches the developing fruit.
Selecting the Right Support System
The correct support system depends heavily on the tomato variety you are cultivating. Tomatoes are classified as either determinate or indeterminate, based on their growth habit. Determinate varieties grow to a fixed, bushy size, typically between three and four feet tall, and produce most of their fruit within a short period, making them well-suited for lighter support systems. Indeterminate varieties are vining plants that continue to grow, flower, and produce fruit until frost, often reaching heights of six to ten feet or more, demanding much sturdier structures.
For determinate plants, a simple staking method or a robust, tall tomato cage works well. Indeterminate plants require heavy-duty support, such as the Florida weave, a single-string trellis system, or a very tall, strong cage. The Florida weave involves driving tall posts, such as metal T-posts, at the ends of the row and running twine horizontally between the posts and the plants as they grow, effectively creating a basket of support. A single-string trellis, common in commercial settings, uses an overhead wire or beam from which a single piece of strong twine is dropped to each plant, training the main vine upwards.
Installation Timing and Technique
The support structure must be installed either before or immediately after planting the tomato seedlings to prevent damage to the developing root system. Driving a stake or post near a mature plant can sever roots, stressing the plant and reducing its ability to take up water and nutrients. For individual staking or caging, the support should be buried at least 12 to 18 inches deep to remain stable under the weight of a mature, fruit-laden plant.
When setting up a Florida weave, end posts must be anchored securely, as they will bear the significant horizontal tension of the woven twine and the full weight of the row. Posts, typically seven to eight feet tall for indeterminate varieties, should be driven deeply into the ground. For a string trellis, the overhead support wire or beam must be capable of holding hundreds of pounds of plant and fruit weight. The individual support strings, often made of polypropylene or natural twine, are then anchored to the ground near the base of the plant with a landscape staple or a loose knot at the stem base.
Pruning and Training the Vines
Once the support system is in place, the ongoing process of pruning and training is necessary to guide the plant’s vertical growth. Training the vine involves securing the main stem to the support structure to ensure it grows upward. For indeterminate tomatoes on a string trellis or stake, the main vine should be tied or clipped to the support every six to twelve inches as it grows.
Use materials that are gentle on the stem, such as soft cloth strips, specialized plastic clips, or biodegradable twine. When tying the stem, employ a loose knot or loop to prevent the material from girdling the stem as the plant thickens. Girdling would restrict the flow of water and nutrients. The physical act of training should be done weekly, or as soon as the plant has grown enough to require a new point of attachment to keep the vine upright.
Pruning involves the removal of “suckers,” which are small shoots that emerge in the axil, the point where a leaf stem meets the main vine. These suckers grow into full secondary vines that compete for the plant’s energy. They are usually removed, especially on indeterminate varieties grown with a single-leader system. Removing suckers directs the plant’s energy toward producing larger, earlier fruit on the main vine, and it also improves air circulation within the plant canopy.
The best practice is to remove suckers when they are small, ideally less than two inches long, by simply pinching them off with your fingers. If a sucker has grown large and woody, use a clean pair of pruners to avoid tearing the main stem. For determinate varieties, suckering is not typically necessary, as it can reduce the overall yield. However, the lower leaves that touch the soil should be removed to reduce the chance of disease splash-back.