Mosel, Germany, has long been known for producing top-quality Rieslings with complex flavors and bracing acidity, due to the cool climate.
Typically, the wine growing regions of the world fall in between 30 and 50 degrees latitude in each hemisphere. Mosel sits at 50.4, pushing the envelope for what is considered a typical wine region. Luckily, Riesling is a grape that can tolerate cooler climates. Additionally, the topography of the Mosel valley provides several key features that help with grape ripening. First, the Mosel River which snakes through the valley reflects the sunlight onto the vines. Also, the river will help moderate the ambient temperature in the evenings by radiating the heat it has absorbed during the day. Second, the steep slopes along the river allow grape growers to orient the vines so that they can get the most sun exposure possible during the day.
German Rieslings illustrate the delicate balance that needs to exist among acidity, sugar and alcohol. As sugar levels within the grape rise, acidity levels fall. The cooler climates in Mosel have allowed the grapes to maintain high acidity levels, while reaching acceptable levels of sugar. So, even when Rieslings are made in a sweet style, their acidity provides the necessary structure and balance so the wines don’t feel flabby and cloying.
In recent years, it has been harder to maintain that balance. As with other parts of the wine growing world, Mosel has been experiencing an increase in average temperatures, leading to a quicker ripening of grapes and higher sugar levels. Higher sugar levels mean higher alcohol, if the wine is fermented to dryness. Where you could once easily create a dry, low-alcohol Kabinett style wine, you are now seeing those alcohol levels creep up, or you are seeing Kabinett wines with more residual sugar in order to keep the alcohol lower. Spatlese and Auslese wines are developing even more sugar from their extended time on the vine, leading to even sweeter end products.
Winemakers are doing what they can to manage, which includes reducing the amount of leaves on the vine and doing more selective picking of grapes. Fewer leaves leads to less photosynthesis so the vines are not producing as much sugar to store in the grapes; however, fewer leaves means less shade for the grapes which can lead to sunburn.
Dr. Leimbrock winery focuses on making dry and semi-dry Rieslings. Their grapes come from the prestigious Brauneberger Juffer and Juffer-Sonnenuhr vineyards, with extremely steep, south-facing slopes (60-70 degree grade), providing the best possible conditions for growing Riesling. To deal with the increases in average temperatures, they are using a more selective approach to grape picking to achieve their desired results. Harvesting grapes on the steep slopes is already labor-intensive enough. But now, they are adding in the extra layer of evaluating each bunch and picking just the ones they want for each of their styles of wine. This means multiple passes through the vineyard during harvest months. The end result is wines that continue to demonstrate that balance of sugar and acid that makes German Riesling so great.