VSP (Vertical Shoot Positioning) Trellis System

VSP is a vine training system in which shoots are directed vertically upward in a narrow, hedge-like curtain. The fruiting zone sits on a lower cordon or cane wire, and multiple pairs of movable catch wires above it hold the growing shoots in an upright position throughout the season. The result is a tidy, well-defined canopy panel that allows sunlight to penetrate the fruit zone and facilitates efficient spraying and mechanical operations. The system works with both spur-pruned bilateral cordons and cane-pruned configurations, making it adaptable across varieties and regions.

• Wire framework: typically a static fruiting wire plus 2-3 pairs of movable catch wires above, totaling 4-6 wires per row
• Fruiting wire height varies by region and climate, from about 20-30 cm in Champagne to 100-110 cm in California
• Compatible with both bilateral cordon spur pruning and unilateral or bilateral cane (Guyot) pruning
• Particularly well suited to the naturally upright growth habit of Vitis vinifera cultivars

During spring growth, elongating shoots are tucked between or behind the pairs of catch wires, which are progressively moved upward as the season advances. Locking the wires in place positions the shoots into a narrow vertical panel. Mechanical or hand hedging trims the canopy top and sides to maintain a consistent height and prevent excessive lateral growth from shading the fruit zone. Selective leaf removal around clusters improves light penetration and airflow, reducing fungal disease pressure. The vertical orientation forces fruit clusters to the outside of the canopy, enhancing their exposure to sunlight and improving ripening under cool-climate conditions.

• Catch wires are manually or mechanically moved upward and locked into clips or notched stakes as shoots elongate in spring
• Hedging is performed 2-4 times per season to control canopy height and limit shading from lateral shoot regrowth
• Leaf removal in the fruit zone improves light penetration, airflow, and the effectiveness of spray applications
• Vertical shoot orientation maintains apical dominance, intensifying shoot vigor and supporting full canopy development in marginal climates

VSP was first adopted in cool, humid regions including New Zealand, Germany, and France, where its open canopy reduces the chronic risk of botrytis and powdery mildew. The upright shoot orientation maximizes the area of leaf surface exposed to sunlight, which is especially valuable where heat and light are limiting factors for ripening. In warmer climates, VSP remains common but requires careful management: the system's narrow, thin canopy can expose berries to damaging sunburn, and in high-vigor sites it may produce excessively dense foliage that negates its benefits. Fruiting wire height can be adjusted to manage fruit zone temperature, with research showing that raising the wire from 45 cm to 95 cm can reduce maximum daytime temperatures by 0.4-0.6°C and raise minimum frost-night temperatures by 0.2-0.5°C.

• First widely used in cool, high-humidity regions: New Zealand, Germany, and France, where disease risk is highest and light capture is most critical
• VSP trellises were a popular choice for California winegrape vineyards during the industry expansion of the 1990s, though the narrow canopy can expose berries to sunburn in warm, sunny climates
• Fruiting wire height adjustment offers a meaningful tool for managing frost risk and fruit zone temperature across climates
• Less suited to very high-vigor soils or sites; on such sites, divided-canopy systems such as GDC or Scott Henry may better manage excess vigor and achieve vine balance

When properly managed, VSP positions clusters at the canopy exterior where they receive direct sunlight, supporting phenolic and sugar development and producing clean fruit with well-defined varietal character. Adequate leaf area relative to crop load is critical: research by Kliewer and Dokoozlian (2005) established that single-canopy systems require 0.8-1.2 m² of leaf area per kg of fruit for maximum soluble solids, berry weight, and color. In cool climates, this exposed canopy architecture is a key tool for achieving sufficient ripeness. Conversely, on vigorous sites where the canopy becomes too dense, shade-related issues can produce suboptimal fruit color, excess herbaceous character, and higher disease incidence.

• Fruit clusters pushed to the canopy exterior receive improved direct sunlight, supporting sugar accumulation and color development
• Recommended leaf area to fruit weight ratio for single-canopy VSP systems: 0.8-1.2 m² per kg fruit (approximately 8-12 cm²/g) for optimal ripeness
• In cool climates, the large, well-exposed leaf surface supports photosynthesis and increases the likelihood of reaching full canopy under marginal heat and sunlight
• Dense canopies resulting from excessive vigor on VSP can create shade, increasing fungal disease risk and producing elevated herbaceous characters in the fruit

VSP first gained widespread use in cool European and New Zealand wine regions before spreading globally. In New Zealand, standard VSP trellising became the established starting point across Marlborough's rapidly expanding Sauvignon Blanc vineyards, though some producers have since trialled divided-canopy alternatives on higher-vigor sites. Dr. Richard Smart, as New Zealand's Government Viticultural Scientist based at Ruakura Research Station in the 1980s, was instrumental in formalizing canopy management principles for the region. His consultancy Smart Viticulture, founded in 1990, carried these principles to over 300 clients across approximately 40 countries. In the United States, VSP became the dominant system during the California vineyard expansion of the 1990s, particularly on Napa and Sonoma estate vineyards with moderate-vigor sites.

• Marlborough, New Zealand: VSP established as the standard training system across the region's Sauvignon Blanc expansion; some high-vigor blocks have since shifted to Scott Henry or other divided-canopy alternatives
• California: VSP became the leading choice for premium estate vineyards during the 1990s industry boom, valued for its compatibility with mechanization and quality focus
• Dr. Richard Smart's 'Sunlight into Wine' (1991) won the OIV Award for Viticulture and is dedicated to his mentor Nelson Shaulis, Cornell professor and developer of the Geneva Double Curtain
• Fruiting wire configuration varies substantially by regional appellation rules and tradition; Champagne, for example, sets the wire as low as 20-30 cm to comply with strict AOC requirements

VSP's primary strengths are its compatibility with mechanized vineyard operations (hedging, harvesting, spraying), its suitability for Vitis vinifera's naturally upright growth, and its well-documented effectiveness in cool-climate disease management. Its principal limitation is on high-vigor sites, where the single narrow curtain can become too dense to achieve vine balance, limiting yields to below economically viable thresholds on some warm-climate California vineyards. In these cases, divided-canopy systems such as the Geneva Double Curtain (GDC), Smart-Dyson, Scott Henry, or Lyre offer more leaf area per vine and better canopy openness. VSP's relative simplicity and lower trellis material costs compared to divided-canopy systems make it the default choice for new plantings across most cool and moderate-climate regions worldwide.

• Key advantage: strong compatibility with mechanized hedging, selective harvesting, and spray equipment, reducing ongoing vineyard labor costs
• Key limitation: on high-vigor or fertile sites, the narrow single curtain can become overly dense, creating shade, disease pressure, and herbaceous fruit characters
• Alternatives for high-vigor sites: Geneva Double Curtain (GDC, developed by Nelson Shaulis, 1960s), Scott Henry, Smart-Dyson, and Lyre systems all divide the canopy to improve light exposure and vine balance
• VSP's lower trellis installation cost and simpler wire configuration relative to divided systems make it the default in most new premium vineyard plantings globally