Super warm summer great for Minnesota apples and wine grapes

Our warm Mediterranean-style summer has been a boon for Minnesota wine grapes and apples.

This 5th warmest summer and warmest September on record in the Twin Cities helped add sweetness to fruits this season. Overall temperatures have run more than 3 degrees warmer than average since June 1.

I paid a visit to the University of Minnesota Landscape Arboretum in Chanhassen this week.

I spoke with John Thull who researches cold-climate grapes and wine with the Arboretum. And John Thull knows a lot about Minnesota wine grapes.

I aksed John about our warm summer and the impact on Minnesota’s wine grapes and apple crop.

Here are some excerpts from our conversation.

Paul Huttner: “Alright John. It’s October already, still 90 degrees. Tell us how the grapes did this summer?”

John Thull: “The grapes did really well with the heat that we had from the beginning of the season on. It was a beautiful ripening season for the grapes. The drought and the dryness help facilitate making those really good flavors in the grapes and lowering the acid. Making the chemistry of the juice taste really good this time of year.

The grapes ended up being really good throughout September. Then as you know toward the end of September we got heavy rains. And so some of the grapes started splitting their skins. The varieties that are more tender and split-prone.

PH: Are you able to gauge yet how good this year’s grape crop was compared to other years? Is it one of the better years?

JT: Fruit quality-wise it’s one of the better years for sure. Whenever you have that heat combination it really makes the flavors taste great. As far as yield that’s kind of hit or miss depending on the grower you’re talking to. Some people saw increased yields. Some people saw decreased yields.

Basically, we’ve had a few years of droughty seasons now. And that starts to impact the vine at some point. So the water stress does kind of affect the yield from year to year. And basically, since the fruit is initiated the previous season whatever happened last year is really impacting our yields this year.

So with a few years of drought, you see a little lower yield. But with the flavors increasing it should make a better wine ultimately which is the best part of all of it.

PH: So the wine grapes actually have kind of a climate memory?

JT: Yeah, we always think of it sort of like a memory. They sort of log that into their trunks almost. Each ring that gets put on each year like tree rings sort of logs the previous season. A few seasons back even will impact the life of that vine. It’s kind of a cool plant that way.

PH: And the growers that you’re talking to around Minnesota. How are they doing these last 3 summers where we’ve gone from wet springs into drought?

JT: They’re doing alright. The growers that I’ve talked to especially people that have been establishing new vineyards, I’ve been watching them increase their yields over time. I feel like some people who had their vineyards established in the mid-2010s, we saw Polar Vortex in 2014 and again in 2018. So those vines had accumulated some of those trunk issues with cold injury or fungal issues in the trunks because of that wet and cold seasonality. That weakened the trunks essentially. So to fix that you can start growing a new sucker, rejuvenating your vine, and making it stronger from the ground up.

PH: And what about the apple crop this year with the hot droughty summer?

JT: The apples fared well for the most part. Some trees were starting to show signs of drought stress in their leaves. Nothing that they can’t tolerate as long as rains return before the next growing season. Overall the fruit quality os good. We’re seeing good flavors across different apple varieties with extra sweetness from all that intense sunshine that we’ve had this year.

I can attest to that. The bag of Honeycrisp apples I bought at the Apple House this week is extra delicious.