JamesSuckling Interviews: Katharina Prum

JamesSuckling Interviews features innovative and influential winery owners, winemakers and industry notables representing the new generation that is shaping tastes, trends and techniques in the greater wine world. 

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The Joh. Jos. Prum winery in Germany’s Mosel Valley has been putting top-tier German riesling on the global wine map for more than 100 years, setting continued high standards for freshness, finesse and ageability. Taking over the estate in 1969, Manfred Prum championed a benchmark style best showcased with a decade – and often much more – years in bottle. After leaving a career in law and joining her father at the Middle Mosel estate in the village of Wehlen, Katharina Prum has continued the legacy as primary winemaker.

JamesSuckling.com’s Susan Kostrzewa talked with  Katharina about how she keeps a cool head in the face of jarring climate surprises; understanding the difference between sustainable and organic farming; the growing global appreciation for cellar-worthy white wines and how wine connects and “brings cultures together.” The interview has been edited for length and clarity.

Let’s start by talking about the challenges of the 2022, which was one of the hottest and driest on record for the Mosel, and the 2023, which was especially wet, with extreme rainfall running the risk of infections and mold in the vineyard. How did you navigate these vintages and how do you think your experience now in winemaking has helped you navigate what you're experiencing with these extremes?

I think experience helps because it helps you to be calm. I grew up on the [Joh. Jos. Prum] estate, in the building itself, surrounded by the whole production and with the knowledge that you cannot predict things, that you have to face challenges.

In those days, the main concern was how to get enough ripeness. The Mosel is a cool climate, and still is relatively cool. That usually meant to my father that we needed to wait as long as possible in picking to get ripeness, but also take a high risk, because the longer you wait and the more you go into October and November, the weather got more unstable.

But I think the kinds of challenges have changed more recently. The 2022 vintage for me was the most extreme experience because we had this tremendous dryness. Dryness was something that I grew up with and our slope where we grow wine has a fantastic water supply, so lack of water was not previously a concern. I realized this is not necessarily the fact any longer in ‘22.

From April to early September – in this main ripening period, spring, after bud break to just before harvest – there was almost no rain. Our reaction was to carefully observe the vineyards and to cut off a lot of grapes, which is usually something we don't like to do in that amount as you can easily bring imbalance to the vine.

I’m convinced it was the only chance to guarantee the ripeness of the vintage and also save the long-term health of the vines. 2023 was not as challenging because this excess rain is something we've known in the past. But what is clear is that there are a lot more extremes.

In the face of these more unpredictable and challenging conditions in the Mosel, making precise decisions requires not only expertise, but the level-headed patience you just mentioned. Do you see this as a challenge for producers in the region who might be more reactive and risk averse?

The majority of growers here have grown up with wine, so most estates have a long viticultural history. However, there are also quite a few new people in the region, which I think is fantastic because it also brings new energy and new perspectives. Most of them have worked in wineries before and then decided to establish their own estates. But I think if you decide to work with nature, and you want to make your hobby a profession, then sometimes it can be challenging. And they often get frustrated very quickly.

For me, it helped that I started to work with my father in the 2003 vintage, which was quite an extreme year. It was very hot – much hotter in the south of Europe, but still comparatively hot here also. I remember some growers almost were panicking – younger growers who were less experienced – and they stopped my father and said, “What do we do?” Because sugar levels went up, acidity levels went down. My father had already done many vintages and had a long perspective.

That helped me to learn, to also be calm. In 2022, I saw some examples where experienced growers did not consider the consequence of green harvest enough. And this was a disaster. If you had too-high yields in that year, the vines just stopped developing and the grapes I saw in some parcels I could not even have harvested because you could not do a proper wine with it. But we all learn every year and there are always new aspects we add to our experience.

Some producers have talked about the silver lining that climate change has brought, despite its obvious negatives. Do you feel your wines have been positively affected by these warmer and drier conditions?

The climate warming has definitely helped because in the past, as I mentioned, we did not get enough ripeness. That was a problem until the early ‘90s. Today, we have these extremes and we have to face them, and while it's less stable, if you know how to deal with it, you are able to produce a better range of vintages; a wider range of wines with different ripeness levels, etc.

We have not had any bad vintages since the early ‘90s. Humidity can be a problem, but that has always been a problem, especially during harvest. So you just have to be super selective. But the fact that we are able to get enough ripeness every year is a big difference and a positive change.

What makes your rieslings so fresh and primary on their release?

There are a lot of different aspects. First, you have to treat your vines well throughout the year and try to do the best in the given situation. You cannot predict the future; we can maybe foresee the forecast for the next two or three days, but no more.

We have to work with all the experience we have collected in the past and observe and react. Then it's essential to harvest each parcel at the most ideal time. Maybe you harvest a whole parcel in one go, or maybe in five goes. Of course, it's 100 percent manual picking, so you also have to have an experienced team. How to harvest, how to select, that is very important.

And then I think in the cellar it's just doing as little as possible. When the grape is harvested, we want our goal to be 100 percent reached and we try not to lose any percentage after that. We never add cultivated yeast. We ferment in stainless steel, which is super neutral. We don't pressure the wine, so the fermentation might take a week, a month, or a year. We let this particular tank decide how long it takes.

In your cellar, what is the constant ambient temperature, and do you ever offer tours there?

The temperature varies because it's not a temperature-controlled cellar. It's below the estate building, in the earth which breeds natural chilling. In winter it gets maybe down to 5 degrees Celsius (41 Fahrenheit) or so. In summer it gets well over 10. So maybe 12, maybe 13, 14.

On tours, no, as we don’t have a show cellar. It's a working cellar that grew over the decades. My father took some people to the cellar years ago. They were super disappointed because they had seen beautiful cellars elsewhere. And the house itself is a beautiful building. You have an idea of what cellar you expect and ours has the tanks, the bottled wines, and there is no order because it was developed step by step.

Your old as well as ungrafted vines are a unique feature of your estate. How do your old vines assist in management of the changing climate?

About 90 percent of our vines are ungrafted, which is a very high percentage. And it's a very rare thing because, as you know, most regions worldwide cannot have ungrafted vines. But the Mosel, with its slate soils, is one of the few regions, few soils that can have ungrafted vines.

Our old vines we appreciate more and more, especially coming back to the 2022 vintage and years when we have these extremes, because the old vines have deeper roots and can handle these extremes much better than young vines.

When we did the green harvest in 2022 we specifically had to look after those vines that were in their first years, which fortunately is not a big portion for us. They were really struggling. They were full of energy and then they had no water. If we had not reacted at all, they might have died.

You’ve been open about working sustainably in the vineyard but not committing to organic or biodynamic practices. Can you talk more about that?

Organic and sustainable are for me two very different things. Sustainable means really working as close to and for the good of nature. Not just for your piece of land, but for the ecosystem.

Organic for me is a different thing. As in life, there is no black and white and organic is not necessarily better for nature. For example, you need to spray much more often, which means more CO2 emissions. We are partly organic, just to see also how the vineyards react to it, how the soils react to it, but not fully committed.

The topic I struggle a lot with is the topic of copper, because copper [used in fungicide] is a heavy metal. It never disappears from the soil. There are treatments that have been allowed in organic growing in the past and in my opinion, for political reasons and not for scientific reasons, they have been forbidden.

Now there are discussions to allow them again, which shows it's not something always proven scientifically or decided by scientific reasons. I think unfortunately as a grower we have to put much more energy into determining what is best for nature and what is the best for our soils.

So it’s more of a personal process and ongoing evolution.

I think in all the little steps you have to make your own decision and you need to feel good with it. And sometimes you don't feel 100 percent good with it, but you feel in the end it's the better solution.

One aspect, for example, is using herbicides. We don't do that. But of course it means that you have people that work really hard in very, very steep slopes and have to remove the bad weeds by hand. And sometimes I ask myself, is it really responsible to do it?

It goes beyond the vineyard. We all learned more recently what a big impact the weight of the bottle has on the worldwide CO2 emission. I always had an awareness, in the last two or three or years I read some articles and saw some statistics, and was surprised with how big the impact is.

I'm glad that traditionally the most legal green bottle we use is quite light in weight. We had one bottle that was heavier and while beautiful, we stopped using it because it was maybe 20 percent heavier.

Ageability is a hallmark of Mosel riesling, and your wines are considered among the top tier of cellar-worthy whites in the world. Do you think the modern consumer is becoming increasingly respectful of the need to hold complex white wines? How have you appealed to consumers who might not understand this?

Growing up, we never opened a super young bottle in the family just for fun. I remember my first visit to the U.S., and I was completely shocked that people thought they had to drink the wine immediately. Worldwide, I think that is changing.

When I do tastings, seminars, masterclasses, I always say to think of or treat these wines as you would a red wine that you want to age. But I don't say not to open a ‘22 or even just-bottled ‘23 Kabinett. On a hot summer day in the Mosel Valley, it's super fun to have this and enjoy this, but you get a completely different experience if you let that wine age five, 10 or more years and you can age a Kabinett – the entry level of the predicate wines – for 20 or 30 years without any problem.

There are more people worldwide that appreciate rieslings. The collector’s scene is becoming wider. It's not just Europe and the U.S. There are a lot of wine collectors and wine lovers in Asia. In Australia, for example, I think the knowledge is growing. I’ve seen that people who appreciate riesling tend not to stick to just one region or producer and want to try more things.

Also as I mentioned, food pairings. Ten to 15 years ago in France for example, there were often few non-French wines on restaurant menus, and now, top restaurants in Paris are asking, can we have a few bottles of something aged because we want to show it to people? These requests show more awareness. It’s slow but I think it's developing in a very good direction.

What do you consider to be new areas of opportunity for Prum and for the region?

We produce 100 percent riesling and have decided not to change that. We still feel it's the absolute ideal grape variety for our relatively cool climate. There are other, warmer regions that produce fantastic rieslings, so that gives me hope to see what happens there. There are regional producers who plant syrah and chardonnay, and visitors to the winery have said they tried their first syrahs from the Mosel and were very positively surprised. So I think overall there are opportunities for new grape varietals now.

Beyond varietals, I'm very optimistic for our region as far as worldwide sales and recognition for our wines are concerned, because I think this style of wine is something that appeals to more and more people. The relatively low alcohol levels that we have here is a very important aspect.

'I'm very optimistic for our region as far as worldwide sales and recognition for our wines are concerned'

It used to be almost an obstacle in the past because, as you know, there were waves when people were looking to 16-plus percent on the label. And I remember 20 years ago when I was discussing with a U.S. importer what to mention on the label besides the legal conditions you have to put on it. We suggested including the relatively low alcohol content and they said, no, no, don't do that. This is when Californian wines were very much in vogue.

People are now much more conscious about alcohol levels. Also, the style, especially the pradikat wines that we produce, are fantastic for food pairing. And I think this topic of wine and food pairing is much more important than in the past. People are much more adventurous. And of course, we are a niche worldwide. I think to increase the niche a little bit and create more awareness – including for the lesser-known growers, is a big opportunity.