Grapevines are vigorous, climbing plants known botanically as lianas. These woody vines naturally seek external structures, like trees, to support their considerable weight and reach sunlight. Providing an engineered support system is the single most important structural decision a grower makes, determining the vine’s shape, productivity, and long-term health. Without external training, the vine’s natural growth habit would result in a sprawling, low-lying mass incompatible with successful cultivation. The chosen structure dictates how the plant is trained and pruned, influencing everything from vineyard accessibility to grape quality.
The Necessity of Vertical Support for Grape Health
Grapevines produce a significant amount of vegetative mass and fruit, often weighing down the canes and shoots until they break or lie on the ground. Vertical support manages this heavy load, preventing physical damage to the vine structure and keeping the developing fruit away from soil and pests. Lifting the canopy off the ground dramatically improves air circulation, which helps mitigate fungal diseases like powdery mildew and downy mildew. Disease pressure is lowered when moisture is allowed to dry quickly within the dense foliage zone.
The positioning of the canopy also ensures optimal sunlight penetration, which is necessary for fruit ripening and sugar production. Sunlight exposure is required not only for the current year’s crop quality but also for the maturation of the wood that will bear the buds for the following season. A well-defined vertical structure organizes the vine’s growth, making routine cultural tasks like pruning, leaf pulling, and harvesting far more efficient.
Selecting the Right Support System
The choice of support system depends primarily on the grower’s goals: maximum production efficiency or aesthetic appeal. The most common structural category is the trellis, which uses posts and wires to support the vine in a mostly vertical plane. Trellises are highly adaptable and are the standard in commercial vineyards because they facilitate canopy management and allow for narrow-row spacing. They channel the vine’s energy into a defined, two-dimensional fruiting zone.
Alternatively, the arbor or pergola system trains the vine horizontally over an overhead structure, often used in home gardens for shade and ornamental purposes. This system allows the heavy canopy to be draped high above, creating an accessible space underneath. While it provides excellent protection from excessive sun or rain, it is generally less efficient for high-volume fruit production.
A third, less permanent option is simple staking, typically used for young vines to provide initial support before the main trellis is constructed. Staking alone is not practical for mature, fruit-bearing vines due to the sheer weight of the crop and foliage. The decision between a vertical trellis and an overhead arbor is essentially a choice between maximizing viticultural precision and prioritizing garden landscape function.
Key Trellis Systems and Their Applications
Once a trellis is chosen, the specific training method determines the vine’s geometry. The Vertical Shoot Positioning (VSP) system is widely used in premium wine regions, particularly for Vitis vinifera varieties grown in cooler climates. VSP utilizes a stationary lower wire, called the cordon wire, and multiple pairs of movable catch wires above it, often spaced at 10- to 12-inch intervals. Shoots are trained vertically and tucked into these catch wires, creating a tall, narrow canopy.
This narrow, upright structure minimizes shoot crowding, ensuring that the fruit zone receives dappled light and excellent ventilation. This promotes uniform ripening and reduces fungal risk. While VSP is labor-intensive due to the shoot positioning required, it is suitable for mechanical operations and allows for tighter row spacing. However, VSP is less effective in high-vigor sites where the dense foliage can become scrunched within the wires, leading to poor light capture.
For high-vigor varieties and higher-yield table or juice grapes, systems that divide the canopy are preferred, such as the Geneva Double Curtain (GDC). The GDC system trains the vine along two high wires, typically set about 1.8 meters (six feet) above the ground and 1.2 meters (four feet) apart, splitting the canopy into two distinct curtains. This horizontal division maximizes the exposed leaf area, accommodating the plant’s robust growth and increasing its yield potential. The high placement and downward shoot growth of the GDC improve air circulation and sunlight exposure within the fruit zone, although working at this height can be physically demanding.
Building and Maintaining the Support Structure
A robust support system begins with strong end posts, as these bear the brunt of the wire tension and the vine’s accumulated weight. End posts, often 8 feet long and 4 inches in diameter, must be set deep into the soil, generally at least 2 feet, and secured with bracing or anchors to withstand the immense forces. Line posts, which are slightly smaller, are placed every 24 feet along the row to maintain the wire height.
The wire itself should be durable, with galvanized steel being a common choice to prevent chafing of the vines and resist corrosion. Wire gauges commonly range from number 9 to 11, selected for their strength and tension capacity. Specialized tensioning devices, such as turnbuckles or cranks, should be installed at the end posts to allow the wires to be tightened annually to maintain the structure’s integrity.
Ongoing Maintenance
Ongoing maintenance involves checking the hardware and adjusting the wire tension every year before the growing season begins. Posts should be inspected for rot or damage, particularly if they are wood, and repairs should be made promptly to prevent collapse under the heavy summer load. Proper construction ensures the system will support the vine for decades, making the initial investment in durable materials worthwhile.