We harvested St. Pepin on Monday. This variety is time-consuming to harvest because it is located in three of our vineyards, all located around Oskaloosa. We have to move equipment to each vineyard. We expect to harvest Edelweiss and Marquette later this week. These varieties also take a lot of time. In this case, each variety is located in one vineyard but we have 17 acres of Edelweiss at Tassel Ridge and nine acres of Marquette at Meadowcreek West.
Last week, we harvested Brianna. Together with the three varieties we hope to harvest this week, we’ll have four of the 16 different grape varieties that we grow in our vineyards harvested by the end of this week if everything goes as planned. We will actually harvest fruit from just 13 varieties. Three of the varieties are not yet producing. We have added five grape varieties in recent years in pursuit of alternatives to help us make better wines. At this point, the new grape varieties are experiments that offer some interesting potential either as stand-alone varietals or as components in blends. For example, we’ve already concluded that a small amount of Petite Pearl helps to improve our Marquette.
So, how do we decide when to harvest a grape variety? First, we will taste a grape or two from the variety we are assessing. Does it taste ripe? How are the flavors? One of many considerations is the feeling in our throats about 30 seconds after we taste it. If we get a really scratchy feeling in the back of our throats (I describe it as a hand that has grabbed hold of my tonsils and is pulling down…hard!), we know that the acid and particularly the malic acid is too high. We will take a random sample of individual grapes from many bunches of each variety and each vineyard bloc and put them in zipper bags. In the lab, we’ll just crush the fruit by squeezing the bag until we have some juice. We test the juice for total acidity (TA), the strength of the acid (pH), and sugar.
In general, as grapes ripen, the acidity declines, the pH increases (indicating that the acid has gotten weaker), and the sugar increases. Ideally, we’d like the sugar to be in the 22–23% range (that would yield about 12% alcohol by volume in the finished wine but some of our varieties like Edelweiss develop funky flavors if they hang that long. So, we will harvest at about 17% sugar and then add sugar before we ferment the juice so that we’ll end up at about 12% alcohol without the funky flavors.
If your vision of harvesting is a large number of pickers toiling in the hot sun cutting bunches of grapes and putting them into picking totes, it needs to be updated. Today, many smaller vineyard operations do pick by hand but with 75 acres of vines, that is not practical for Tassel Ridge Winery. The problem is that once we’ve determined that a grape variety is ready for harvest, we’ve got 24–72 hours to get those grapes harvested. And, two or more grape varieties may get to optimal ripening at the same time. Furthermore, weather plays into harvesting decisions. If a rain storm is expected in 24 hours, we are going to want to get grapes that are ripe in before the storm hits. Rain will actually dilute the juice for a few days and it will also increase the chances for fungus growth in the form of powdery mildew or sour rot. And, a summer storm may bring hail that can damage ripe fruit.
At Tassel Ridge, we use a mechanical harvester that can pick about 1 ½ tons every 20 minutes. This works out to an acre every 40 minutes. The harvester picks by shaking the grapes off the vine and moving them to a conveyor that takes them to the next row where a tractor-pulled trailer with three ½ ton Macrobins moves alongside the harvester. The harvest crew consists of the harvester driver, tractor driver, and at least one person on the trailer removing any foreign matter that gets “picked.” This could include a bird’s nest, metal clips from the trellis, or even an occasional snake or bat.
Normally, we start harvesting at about 3 a.m. which is the coolest time of day. When the three Macrobins are full, the harvesting stops for a few minutes and the tractor heads for the crush pad at the Winery.