By Andi Anderson
Harvest may mark the end of grape picking, but it is not the end of vineyard management. The period after harvest is one of the most important stages of the year because grapevines begin preparing for winter and the next growing season. During this time, vines focus on storing nutrients, strengthening wood, improving cold tolerance, and entering dormancy.
Michigan vineyards are highly diverse, with different grape varieties, soils, climates, and training systems. Because of these differences, vineyard management should be based on the specific needs of each cultivar and training method rather than following a single schedule.
Research conducted by Michigan State University has shown that training systems significantly influence vine growth, productivity, fruit quality, and cold hardiness. Studies comparing low-head, high-head, low-cordon, and high-cordon systems found that high-cordon vines often produced greater vine size, higher yields, improved sugar accumulation, and stronger cold tolerance. Researchers concluded that “training system is a physiological treatment, not merely a way of holding vines off the ground”.
Different vineyard systems require different management approaches. Low-cordon vertical shoot positioning systems are commonly used for Vitis vinifera cultivars such as Pinot Gris and Riesling. These vineyards often require careful canopy management and may be more vulnerable to winter injury. High-wire systems are frequently used for cold-hardy hybrids such as Marquette and Marechal Foch, which have different growth habits and generally better cold tolerance.
Growers should also recognize that not all hybrid or vinifera cultivars respond the same way. Varieties differ in vigor, disease susceptibility, fruitfulness, and winter hardiness. As a result, successful postharvest management depends on understanding the biology of each cultivar. Experts recommend “treating the vineyard according to the biology of the cultivar and the architecture of the training system, not simply according to the calendar.”
Following harvest, healthy leaves continue producing energy through photosynthesis. Carbohydrates and nutrients move into roots, trunks, and permanent vine structures where they are stored for the following spring. Research has shown that maintaining healthy foliage during this period improves reserve accumulation and supports root growth.
The importance of this postharvest period varies by grape variety. Early-harvested cultivars often enjoy several weeks of active growth before winter, allowing them to build reserves. Later-harvested cultivars may have a shorter recovery period before cold weather arrives.
Regardless of vineyard type, the primary objective remains the same: maintain healthy, mature foliage after harvest without encouraging excessive new growth. Proper postharvest care helps vines enter winter in a stronger condition, improving survival, productivity, and fruit quality in future seasons.
Photo Credit: istock-jhvephoto
Categories: Michigan, Crops