Sunshine is crucial for ripening the grapes sufficiently to make our precious wine. A hot spell during summer doesn’t harm, and it’s well documented that warm years often produce some of the best vintages. However, many winemakers are confronted with new climatic challenges, notably due to the vines being excessively exposed to the sun.
The problem is that the hotter it gets, the higher the sugar level and so the higher the alcoholic volume. The vineyards most impacted are in the southern regions, where the alcoholic volume of the wines has increased by a degree per decade over the past 30 years. It’s not such a problem for wines with a high sugar content like Sauternes, but other wines such as Pinot Noir, risk losing their intensity and acidic balance.
This is where shade can play a role in winemaking, a simple technique that offers several advantages to protect the vines and improve the quality of the grapes. The shade will help regulate the temperature of the vegetative matter and reduce hydric-stress, and for the grapes, keep the sugar levels down and slow the ripening of the grapes.
Protection from excessive heat
The shade provides a natural protection from direct sun rays, keeping the temperature of the vines lower. When vines are exposed to too much heat, they can be damaged from burnt leaves or grapes, as well as dehydration.
Several techniques exist depending on the region. The first is to stop the practice of removing leaves from the vines. Leaving more leaves on the plant will naturally protect the grapes from the sun and help avoid them from drying out.
Some winemakers choose to train the vines, using up to 5 or 6 training wires, in order that the vines reach 2m high, thus creating their own shade.
In the Rhone Valley, the vines grow around and are attached to large wooden stakes, or échalas. The tops of the vines are weaved together with those from the vines on either side to form an arch. This helps to create even more shade, a technique used effectively at Château Cohola.
Other winemakers are looking to vitiforestry, whereby the vineyards are surrounded by trees that help protect the vines from the heat, help retain water, and fertilise the soils. It’s also a great way to improve the biodiversity in the vineyard!
Keeping the soil damp
Prolonged exposure to the sun means that water evaporates more quickly from the soil, which can cause hydric stress for the vines. Some winemakers therefore choose to leave the cut grass around the vines to create a vegetal carpet. The shade provides a protective layer that slows down the evaporation and keeps the soil damper. By keeping better water reserves in the soil, the vines can better resist dry spells and remain in good health.
Controlling the ripening of the grapes
The grape maturing process is a delicate one, and needs particular attention paid to it. The shade can play a crucial role by slowing the process down. Exposure to too much sun accelerates how quickly the grapes mature, which can have a negative impact on their quality, particularly the development of aromas and taste. By creating shady areas in the vineyard, the winemakers can help slow down the maturing process in the quest to improve quality.
The shade can provide numerous advantages to protect the vines and improve the quality of the grapes. It can help protect the vines from heat damage, better maintain the humidity in the soil, and to control the rate of maturity. The techniques used to help create shade can be adapted to the specifics of each region and local climatic conditions. With careful management, the winemakers can help create the optimal conditions for the vines to prosper and produce better quality wines.
