Ready, Set, Wait!

I live by my calendar. Blocking out certain days is no concern, unless I don’t know when the days are. This is the case while waiting for the grapes to arrive at Vint Hill Craft Winery and Tin Lizzie Wineworks. We are at the mercy of the weather, harvest and shipment. Is there a way to get a ballpark idea of when the grapes may arrive?

Some growers and winemakers believe so. They talk about growing degree days for an educated guess of potential harvest. A degree day is the calculation of the difference between the average temperature for a day and 50. So if the average temperature for a day is 70º one would calculate 70 – 50 and the result 20 is the degree day for that date. Grapevines and grapes do not grow or mature much with temperatures less than 50º. For grapes, degree days are counted from April 1^st through October 31^st. Different grape varieties mature at different ranges of degree days.

Over the years the number of degree days vary by certain dates. This year Napa recorded 2,218 degree days by the middle of September. Last year they recorded that number by September 3^rd. So that would put them about ten days or so behind where they were last year at this time. If you know when the grapes were harvested last year and you add ten days to last year’s date, you might predict about when the grapes will be harvested this year.

Will this reasoning work? There seem to be several variables at play here, one being the average temperatures after the middle of September. There is also the weather that may come into play. Many growers may decide to harvest a few days early if multi-inches of rain is on the way.

Dave Zuchero of Tin Lizzie Wineworks is predicting that Stagecoach vineyard in Napa may harvest the Cabernet Sauvignon the week of October 5^th with delivery the week of October 12^th. We’ll see how accurate this prediction turns out. Meanwhile, I’m ready, set and waiting.