Summer trimming, also called canopy management or hedging, maintains the grapevine’s vegetative growth during the active season. Unlike dormant (winter) pruning, which establishes the permanent structure and sets potential yield, summer work involves selectively removing green shoots and leaves. This regulates the current year’s crop and optimizes the environment around the developing fruit. The goal is to fine-tune the vine’s energy distribution and create an ideal microclimate.
The Goals of Summer Canopy Management
The primary purpose of summer trimming is to maintain vine balance, directing the plant’s energy toward fruit development instead of excessive foliage. Controlling vegetative growth prevents the vine from wasting resources on non-productive shoots. This allows the remaining leaves to efficiently supply sugars to the developing grapes. A balanced vine has enough leaf surface area to ripen the fruit without creating a dense, overgrown canopy.
Manipulating the canopy also affects the vineyard’s internal environment, aiding in disease prevention. Opening the foliage improves air circulation, which quickly dries dew and rain, reducing the risk of fungal infections like powdery mildew and botrytis bunch rot. Increased sunlight penetration to the fruit zone is essential for sugar accumulation, color development in red varieties, and forming flavor compounds. Managing the canopy promotes uniform ripening and optimal fruit quality.
Specific Techniques for Summer Trimming
Summer trimming involves several distinct techniques applied to various parts of the growing vine.
Topping and Tipping
Topping, or tipping, is the removal of the ends of the main growing shoots (apical meristems). This arrests the shoot’s length, redirecting the vine’s energy to thicken the existing cane and develop laterals. When cutting, leave a minimum of 10 to 15 fully expanded leaves past the last fruit cluster. This ensures adequate photosynthetic capacity for ripening the fruit.
Managing Laterals
Managing side shoots, or laterals, which emerge from the leaf axils, is a frequent task. Laterals quickly create a dense, shaded canopy if left unchecked, so they must be removed or trimmed back. Many growers remove the first three to five laterals closest to the cordon or main cane, particularly those in the fruiting zone. Removing these helps maintain an open architecture.
Leaf Pulling (Defoliation)
Leaf pulling, or defoliation, focuses specifically on the fruiting zone. This involves removing leaves immediately surrounding the grape clusters to increase direct sunlight exposure and improve air movement. Perform this carefully to avoid sunburn, especially in hot climates; it is often done only on the morning-sun side of the row initially. Use sharp, clean hand shears or loppers for topping, while shoot and lateral removal is often done by hand when growth is young.
Optimal Timing and Frequency for Summer Work
The timing of summer trimming is linked to the vine’s physiological stage, requiring a phased approach throughout the season. Early summer work, including tipping and shoot thinning, should be completed before or just after fruit set, when clusters are pea-sized. This early intervention controls the vine’s vigor before it expends too much energy on excessive shoot growth, helping achieve the desired balance. If shoots grow beyond the top wire of the trellis and begin to droop, hedging may need to be repeated to maintain the canopy’s shape.
Targeted leaf removal around the clusters is performed later in the season, near veraison, when the grapes begin to soften and change color. Defoliation at this stage maximizes light and air exposure to the ripening fruit without the risk of yield loss. Gardeners should check vines weekly during the peak growing period, looking for visual indicators like shoots dragging on the ground or dense, multi-layered foliage. Maintaining an open canopy is a continuous process, and the frequency of trimming depends on the vine’s rate of growth.