Spring is a fraught time of year for Andy Fles, the vineyard manager for Shady Lane Cellars, a vineyard and winery in northern Michigan’s Suttons Bay. Spring is when bud break happens: when the brown, bedraggled-looking vines burst into greenery. Grape buds break out of the winter vine in delicate shoots and begin the process of producing this year’s vintage of wine grapes. For Fles and other vineyard managers, bud break is a sign of new life, new seasons, and endless possibilities for this year’s vintage.
Bud break usually happens in May, Fles says, depending on heat accumulation. “When that happens, we’re all very nervous because of the frost.” In Michigan, the first few days of warm spring weather are almost inevitably followed by another hard frost — and sometimes several. “Once the green tissue is out, then it’s very susceptible,” Fles says. “It’s not like the leaves on an apple tree that can tolerate below freezing. If we hit 32 [degrees] or below for more than an hour or two, then we’re going to have some damage out there.”
In recent years, bud break has come earlier and earlier. But because the frost often still follows, vintners like Fles must perform mental acrobatic calculations to try to predict their harvest. Average air temperature, monthly rainfall, and sun exposure averages in Michigan’s climate are all changing rapidly. Climate change is affecting the way Michigan’s vintners grow grapes, how they manage their vineyards, and even which varieties of wine they produce. Vineyard managers must find creative ways to account for climate change, including adding more varieties suited to longer periods of warmth. But while this may seem like great news for wine production in the state, weather extremes like those predicted can make it difficult to plan from seed to bottling.
Over the last 60 years, Michigan’s growing season for grapes has gained almost a month. This adds growing degree days — the accumulation over a year of average daily temperatures above a threshold temperature for a particular crop. That’s good news for winemakers in one of the country’s northernmost growing areas. What’s not good news for Michigan winemakers is the increased volatility of weather predicted by climatologists in the decades to come.
Paolo Sabbatini is an associate professor of horticulture at Michigan State University. He’s spent the past nearly 20 years working with wine growers in Michigan, studying the short- and long-term effects of climate change on the industry. For Sabbatini, the big takeaway is that Michigan will remain, as he dubs it, “consistently inconsistent.” Polar vortexes in 2014 and 2015 devastated the region’s crops; Sabbatini and climatologists predict that winter weather will become increasingly volatile and harder to predict, with more violent storms and polar vortexes.
Michigan is home to five distinct American Viticultural Areas, or AVAs, each of which comes with unique soil, microclimate, and growing patterns. All of these, as well as most of the state’s fruit orchards, are on the western and northern coasts of the state. There, the high volume of water leads to more frequent snow. This snow helps insulate against extreme cold by creating a blanket that retains heat and protects the slumbering vines. “The winters are very, very complicated [to predict] in Michigan, because the temperatures depend on a lot of different factors that are related to the huge amount of water surrounding us,” Sabbatini says. “So, the tough winters are the winters when the lake freezes: You lose the lake effect, because there is ice on top of the lake. Because it’s frozen, the lake doesn’t release any more heat throughout the season.”
In 2017, Sabbatini and his colleagues compared historical weather data from Michigan and Napa in California since 1970. While both areas’ average temperatures over the course of a year increased significantly, Michigan’s temperatures swung wildly. In Napa, the temperatures varied from the ideal temperatures for grape growing by 10 percent in each direction. That is, the average temperature stayed within 10 percent colder or 10 percent warmer than the ideal wine-grape growing temperature. In Michigan over the same years, the temperature variation from ideal was 40 percent in each direction.
“This is the consistent inconsistency,” Sabbatini says. “Yes, we’re on a streak of more heat. But the streak comes not consistently, like in Napa Valley and other regions, but with a lot of variability. It’s a bit like the financial market. It’s always going up, but through a lot of different bumps. You always gain in the long term, but in the short term, you can lose. And that’s Michigan weather.”
It’s not all bad news for Michigan’s growing wine industry, though. A longer growing season means more chances for high-quality wines. Advances in weather prediction and in vine breeding and cultivation can mitigate some of the worst effects of stormy weather. Shady Lane’s Fles even sees advantages for Michigan growers compared with growers in other regions: “We have varieties well suited to a cooler climate, and I think we’re going to be that way for quite a while. We’re not seeing the same type of thing that you’re seeing out west, where there’s lots of discussion around whether the region is getting too hot for Pinot Noir.”
As wildfires and extreme heat waves ravage the West Coast wine regions, Fles notices a new group of fruit and wine growers moving to Michigan. One key advantage that Michigan winemakers have is all around us. “We have water security here,” Fles says. Thanks to that lake effect, Michigan winemakers don’t have to rely on irrigation, which saves a great deal of money and bodes well for future growers. Fles recently helped a vegetable farmer from Colorado move to Michigan; that move was prompted in large part by changing access to water.
As the industry grows, Michigan winemakers are crafting increasingly complex and flavorful wines. Certified sommelier Liz Martinez is group director of beverage and hospitality for Backbone Hospitality Group, which owns Mink, Marrow, Folk, and The Royce in southeast Michigan. Since moving to the state five years ago, she’s been impressed by the rapid change in the quality and variety of its wine. Long known for its sweet Rieslings, Michigan now produces competitive, quality red wines, including Cabernet Franc and Pinot Noir, both rather fickle grapes. “If you’re a smart winemaker,” Martinez says, “you can find a way to adjust and find the varieties that work for the area. Michigan may be a standout soon.”