Minnesota might not seem like a hotspot to grow wine grapes, but with some science and a lot of patience, Minnesota has become well known for cold-hardy grapes.
That’s thanks to the University of Minnesota’s Grape Breeding and Enology program, as well as private breeders, who have spent decades developing wine grape cultivars that can survive Minnesota’s harsh winters (most of the time).
Grapes are not new to Minnesota. Wild grapes (vitis riparia) can be found in Minnesota and the Dakotas, said Jenny Ellenbecker, president of the Minnesota Grape Growers Association and owner of Round Lake Vineyards and Winery in Round Lake.
But wine grapes are not native to the area. Using the vitis riparia and other wild cold-hardy grape plants, the university and other breeders have developed cold-hardy wine grapes.
It’s a long process. Matt Clark, who heads the university’s Grape Breeding and Enology program that's based at the Minnesota Landscape Arboretum in Chanhassen, said on average it takes about 15 years to breed a new cultivar (a grape variety that is named and released) that can survive temperatures of 30 below zero or colder.
“Grapes are a fun model to work with. The community is fun, you get a fun product at the end — wine — which people get excited about,” said Clark, who has been with the program since 2015.
The breeding process
In a nutshell, the university’s process to breed a new cultivar begins by taking a grape plant and breeding it with another grape plant. Researchers do this by removing the male or female parts of a flowering plant, and then covering the plant with a paper bag to prevent unwanted pollen from getting on the plant.
Then, a few days later, researchers will add the pollen of their choice and put the bag back on to protect the cluster for the summer. That plant will produce seeds of a potentially new cultivar.
Researchers do dozens of these controlled crosses every year, which gives them somewhere between 8,000 and 10,000 seeds annually. They then work to narrow down the seeds to find the best ones. Some don’t germinate, they run DNA tests on some to see if they have the qualities they’re looking for, with the goal being to narrow down the thousands of seeds to about 1,000 plants for the year, Clark explained.
Why 1,000? It all comes down to space. The vineyard is home to about 10,000 plants, and every year researchers and the elements (winter, diseases, animals) nix about 1,000 of them that aren’t performing as well to make room for the 1,000 new seedlings. They have to do this to keep the pipeline going, Clark said.
“Once we find something in the vineyard that looks good — maybe it’s disease-resistant and it has enough fruit — then we’ll start to make wine, and that takes a couple of years,” Clark said, noting researches make wine with the grapes for multiple years to see how consistently it performs.
The university’s winemaker, Drew Horton, makes 50 to 150 unique batches of wine every year, using a standard process for white and red wines. Unfortunately, Clark says, the university’s winery is a research winery so they can’t sell the wines — or even drink them. They just do a sensory analysis on them by tasting the wines and spitting them out.
“We make a lot of wine, but unfortunately most of it just goes down the drain,” Clark said.
While the university is making the wine, researchers will start cloning the plant (there’s only one of each plant in the vineyard). These clones are eventually sent out to the university’s collaborators who will also evaluate the plant before it gets released.
It takes about 15 years from start to finish to find a new cultivar. About every 10 years the university hopes to release a new cold-hardy grape to the grape-growing public, Clark said.
The University of Minnesota officially began its wine grape breeding program in 1978, according to its website, and it is now known as one of the top wine grape programs in the country as it works to develop high-quality, cold-hardy and disease-resistant wine and table grape cultivars.
The university, in partnership with the father of grape breeding, Elmer Swenson, released two cultivars in 1977, Edelweiss and Swenson Red. The university’s program has since introduced five more wine grapes:
- Frontenac, a disease-resistant grape used to make red, rose and port wines, was released in 1996.
- Frontenac gris, a grape used to make white wine, was released in 2003.
- La Crescent, a very cold-hardy grape used to make white wine, was released in 2002.
- Marquette, a grape used to make red wine, was released in 2006.
- Itasca, a grape used to make dry white wines, was released in 2017.
Ellenbecker says Frontenac Gris, La Crescent, Marquette and Petite Pearl (a red wine grape developed by Tom Plocher of Hugo), are among the most popular Minnesota-grown grapes used to make wine.
As for the university’s next cold-hardy grape, Clark says it’s still too early to tell. They’re “sending a few things out this year to collaborators,” but he doesn’t have any specific details to share yet.
Itasca are the university’s newest wine grapes, which didn’t take as long as other cultivars to be released because it “survived [the harsh 2014 winter] way better than anything else that was in the pipeline,” Clark said.
“This will be the first year we’re actually seeing wines in the marketplace” made with Itasca grapes, Clark said.
Wines made with Itasca grapes tend to be drier, Ellenbecker said. This is a newer way to describe wine made with Minnesota-grown grapes — in the past, Minnesota wines have had a reputation for being sweet, even too sweet.
That’s because the juice from cold-hardy grapes tend to be more acidic, but also high in sugar, Clark said.
“During the wine-making process, the sugar gets converted into alcohol — that’s why we like wine — but it also tends to leave wine that has higher acid than grapes grown in California,” Clark said. “So then sugar is either added back in, or maybe the fermentation stops short, so there’s more sugar in the wine.”
Clark says vitas raparia — the distant parent in some of the U’s cultivars — is high in acid, so when new grapes are bred, some unfavorable characteristics are passed down to the new grape.
“The breeding program has worked, especially in the last few years, on how to reduce the acid, but also maintain winter hardiness,” Clark said.
“Itasca is kind of the first case where we have acid that’s about one-third lower than the parent, and maybe even two-thirds lower than the original vitas raparia, so we’re making progress moving into this area where the acids are lower,” Clark said. “And that’s a huge emphasis on what we’re doing right now.”
Ellenbecker and Clark both encourage people to go out and try more Minnesota wines. Ellenbecker says Minnesota had a bad reputation for its wines because the industry was so new, but now many local wineries are making award-winning wines made from Minnesota-grown grapes.
And she says many characteristics wine drinkers are looking for now — bright, crisp and refreshing — get that way because of the acidity in the grapes.
Clark says he’s noticed many new wine drinkers prefer sweeter wines, and “often even the wines we are drinking today that are very popular red wines, people would be surprised to know they’re probably technically sweet or not completely dry.”