Grapevines can be pruned in summer, a process fundamentally different from the heavy cutting done during winter dormancy. This summer activity, often called “green pruning” or canopy management, focuses on the vine’s current growth rather than its permanent woody structure. The purpose is to remove excess green, leafy material to redirect the vine’s energy. This ultimately improves the quality and characteristics of the developing fruit and ensures the vine maintains balance throughout the growing season.
Understanding the Goal of Summer Vine Management
The primary purpose of summer vine management is to fine-tune the current year’s harvest, targeting quality control. This contrasts with dormant winter pruning, which establishes the vine’s long-term shape and controls the total number of buds for the next season. Green pruning is corrective, adjusting the vine’s real-time growth based on the season’s conditions and the plant’s vigor.
Selectively removing actively photosynthesizing material redirects the vine’s energy toward ripening the existing grape clusters instead of fueling unnecessary vegetative growth. This shift in energy allocation is crucial for developing desirable sugar content and flavor compounds in the fruit. Managing the canopy also improves light penetration and air circulation around the clusters, which reduces the risk of fungal diseases like bunch rot and powdery mildew.
Essential Summer Trimming Techniques
Summer canopy management employs several distinct techniques, each serving a specific function to optimize the environment around the fruit. These methods manage the vine’s vigor and improve the microclimate of the fruiting zone. The three main techniques are shoot tipping, hedging, and leaf removal.
Shoot Tipping
Shoot tipping, also known as pinching, involves removing just the growing tip of a cane early in the season. This small cut stops the cane’s outward growth, slowing the vine’s overall extension and encouraging lateral growth. By interrupting the flow of growth hormones, the vine redirects its resources toward developing the fruit and strengthening the remaining buds.
Hedging
Hedging, or topping, is the practice of cutting back overly long canes that extend past the trellis system. This technique is a more aggressive form of growth control, often removing 30 to 50 centimeters of shoot material at once. Hedging maintains the canopy within defined boundaries, preventing excessive shading of adjacent rows and ensuring all parts of the vine receive adequate light.
Leaf Removal
Leaf removal, or leaf pulling, is the targeted removal of leaves specifically around the grape clusters. This is typically done in the fruiting zone, removing the basal three to five leaves on a shoot. The immediate goals are to increase sun exposure on the berries, enhance air flow, and allow better penetration of fungicide or pesticide sprays. Increased sun exposure is directly linked to improved fruit color, better phenolic development, and reduced herbaceous aromas in certain grape varieties.
The Critical Role of Timing and Light Exposure
The success of summer trimming depends heavily on precise timing, as the vine’s response changes dramatically throughout the season. Most significant canopy adjustments should be completed by late summer to allow the vine to focus entirely on fruit ripening and wood hardening before winter dormancy. Continuing to trim vigorously too late can stimulate secondary, late-season growth, which drains the vine’s stored energy needed for winter survival.
The window for cluster-zone leaf removal is particularly sensitive, with the optimal timing falling between fruit set and just before veraison, the point when berries begin to change color and soften. Performing leaf removal during this period allows the developing fruit to acclimate to sunlight gradually, building up a natural resistance.
Removing leaves too late, such as after veraison, dramatically increases the risk of sun scald, especially in regions with high heat and intense solar radiation. Sun scald occurs when unacclimated berries are suddenly exposed to direct, intense sunlight, which can damage the fruit. To mitigate this risk, growers in warm climates often only remove leaves from the side of the canopy exposed to the morning sun, leaving afternoon shade protection in place.
Early exposure helps the berries develop protective compounds, while late exposure can reduce the production of anthocyanins, delaying ripening and diminishing fruit quality. Adequate foliage must remain to produce the necessary carbohydrates for fruit development, ripening, and storing energy reserves for the following year.