Every summer, the 4th of July creeps up on me. It seems we were just dealing with a late spring snowstorm, and this past weekend, everyone is lamenting the heat wave. Except the grapevines. Grapevines never complain about too much heat. The hotter the better. Ninety five degrees at the end of June...bring it on! Five inches of rain in one night...you bet! Have a seat and watch us grow! If you were to show me a picture of the River Bend vineyard as it looks today, I would be inclined to believe it was mid-August by how much foliage the heat and rain have produced so far.
It is not every year that we experience a truly hot summer here in Wisconsin. In fact, it's pretty rare. The last one I remember was 2014. The past few years, we have reached 90 degrees just a handful of times all summer. So far this season, River Bend has recorded 90+ degrees on five distinct days...that's pretty impressive for the end of June. Because we have a short growing season...relative to grape growing areas like California or Washington...packing as much heat as possible into the summer is favorable to grape development. One of the key components of grape chemistry is organic acid, and in a cool or wet year, acids do not drop as much as we would like. To get organic acids to drop, the vines basically need to sweat them out, so a hot year generally means lower acidity when it comes time to harvest.
So why does the level of acidity matter? Lower organic acids at harvest give a winemaker flexibility in the style of wine they can produce in a given year. Grapes grown in a northern climate like ours are often too high in acid to produce a quality dry red wine. Acidity is balanced by sweetness, and a dry wine that is too high in acid will be tart...and not desirable. A dry wine with lower acid will be smoother and more approachable. As I mentioned, the last year I would categorize as hot here in our neck of the woods was 2014. That year we produced a dry red wine from Marquette grapes that won a gold medal in a professional competition. The heat reduced the acidity, allowing us to make a nicely balanced dry Marquette. It's too early to tell if this season is shaping up to be dry red wine producing, but we are off to a good start. Stay tuned, and we will see what happens come late September.