INDIANAPOLIS – The last three Spring seasons in Central Indiana have experienced frosts late in the season. Late frosts can impact several crops including wine grapes.
According to Miranda Purcell, viticulture extension specialist at Purdue University, wine grapes are really responsive to temperature changes, if the change is gradual.
“Grapevines are really responsive to the environmental temperatures, and so in the fall when the days start getting shorter and it starts getting colder out, they start preparing for dormancy and then as it gets colder and colder, they get more and more. Dormant and are able to withstand colder and colder temperatures, and so if the temperature dropped to 20 degrees tomorrow, they wouldn’t be ready for it. But if it gradually drops a few degrees on average every week, they would eventually be able to stand 20 degrees in December or January. Saying the opposite happens in the spring as the days become longer and the temperatures get warmer, the grapevines start realizing that spring is coming and so they start coming out of dormancy. And they do that very gradually.”Miranda Purcell, Viticulture Extension Specialist, Purdue University
Different varieties of grapes have different average temperatures they grow well in. When those extreme temperatures happen, grape buds are damaged, impacting the crop as a whole. However, it is hard to tell how much damage has been done until it is time for harvesting, according to Blake Trobaugh, a winemaker at Daniel’s Vineyard.
“It’s kind of tough to tell until this time of year, really, how much damage you had in the spring, so we’re kind of just now seeing and realizing that a lot of the fruit that we’re dealing with is from the second secondary fruit, so it means it came on a little bit later, and now we’re having trouble with ripening this time of year.”Blake Trobaugh, Winemaker at Daniel’s Vineyard
What’s next for farmers if these extremes continue? Well, they will have to adapt. Different grapes handle extremely cold temperatures differently than others. Farmers can either change the variety of grapes or move to a different location. In northern Indiana, there are more varieties of grapes because they see more extreme temperatures than the southern part of the state. Globally, grapes grown in Europe are more sensitive to weather extremes. Those areas would have to make bigger changes to ensure wine production doesn’t change drastically.