Where to Plant a Vineyard: Climate

Mark Chien, Penn State University

Climate at the macro, meso and micro levels will leave its imprint on the wine. It is the main reason for vintage variation. Climate will largely determine the suitability of particular grape varieties for a region. At the vineyard site, matching the correct variety, clone, and rootstock to even the most subtle temperature differences due to topographical variations is vital to fruit maturation. A general rule is to look for the coolest possible site that can fully ripen any variety on a consistent basis. Knowledge and data about local climate conditions are crucial to correct variety choice. Low winter temperature may be the single most limiting factor in wine growing in much of the East and across the Midwest and northern U.S. It is important to know the long-term minimum low winter temperatures for the site. Most consider -8ºF to be a general threshold for vinifera varieties. Length of the growing season is determined by spring and fall frost, particularly in northern regions, and is critical to getting grapes, especially late red varieties, fully ripe if they are to have any chance to make fine wine. Elevation can have a significant effect on length of the growing season. The amount and distribution of rainfall during the growing season and particularly after veraison can have a huge impact on quality. In the East, late season weather events such as hurricanes or slow moving low pressure systems can dramatically affect the quality of a vintage. If a dry zone can be found, it’s easier to adjust soil moisture with irrigation than to try to take it away when it isn’t wanted.