A leaf and Mimi Casteel

Regenerative Agriculture and the Future of Viticulture – In Conversation with Mimi Casteel

Picture by Aubrie Legault

Mimi Casteel grew up working in the vineyard and winery of her parents, the co-founders of Bethel Heights Vineyard in Oregon. After graduating from university, she worked in forests, which led her to study forest science and then on to work as a botanist and ecologist for the US Forest Service. She returned to Bethel Heights in 2005 where she worked for ten years, before leaving and creating Hope Well on her own, where she works regeneratively. The climate shocks of 2020 made it clear to her that tackling the climate crisis needs a collective approach, and she now spends time building strategies and networks to help transform agriculture on a global scale. Mimi is one of the trustees of the Regenerative Viticulture Foundation.

In Conversation with Mimi Casteel – Recorded in May 2022

The article below is an edited and very condensed transcript of this interview with Mimi Casteel.

ARENI

Why are trees and forests so interesting to study?

Mimi Casteel

Anybody who has spent time in the forest has marveled at the abundance and sheer diversity of life that can live just in one single tree. Trees really are the structural component that has helped transform this planet into the livable and beautiful thing that it is, by moving water, by storing carbon, by doing all of the incredible communication underground, by feeding the life underground.

Even when you can visibly see how much life is above ground, it is truly dwarfed by what that is feeding below ground, because the above ground biomass is just a is a tiny little fraction of what lives underground.

Trees really are the structural component that has helped transform this planet into the livable and beautiful thing that it is, by moving water, by storing carbon, by doing all of the incredible communication underground, by feeding the life underground.

Mimi Casteel, Owner, Hope Well Wines

ARENI

What does it mean when you don’t have trees around you?

Mimi Casteel

Every ecosystem has evolved in a place according to the pressures that the environment have placed on a particular location. And the plant community that will develop is going to be a direct reflection of what those pressures were. Where there is extreme heat and it’s very dry and maybe the soils have been either depleted over time or they weren’t that they weren’t that generous to begin, the plant life will reflect that.

And so oftentimes we will evaluate an ecosystem and say it’s good or bad, when those words don’t really apply. The plant community that evolves in a place is what is possible at the time.

ARENI

Are there any lessons that we could learn from trees that would help us be better citizens?

Mimi Casteel

There are so many lessons I wish we would learn from trees and forests and plants in general, but first and foremost, it is that they are completely interconnected and completely dependent. One of the things I found fascinating when I first started studying ecosystems is that not only are they connected underground by the mycorrhizal fungi that colonize their root systems, but in a very young stand of trees, their roots will actually graft together. They will go out looking for the roots of other trees and they will graft to each other underground. And that’s for both structural integrity and then also to facilitate the growth of those mycorrhizal fungi and, and being able to communicate quickly and share resources. It is a selfless act.

ARENI

We’re going to jump into regenerative viticulture and agroforestry. Those are words that you didn’t hear until quite recently, but suddenly we’re talking a lot about them. Why is it relevant to talk about trees in viticulture?

Mimi Casteel

We are coming to recognise that single species cropping systems are very detrimental to the landscape, and we need to start challenging the paradigms that we’ve created with industrial agriculture systems and start building layers of ecosystems that also produce food. The idea with regenerative agriculture is to start rebuilding that ecosystem within the agricultural system. Adding layers of photosynthetic and hydrologic capacity to a landscape can be as simple as adding different layers of plant life. The idea would be to start incorporating a tree layer.

While it might sound very idealistic to have our grapevines growing up trees, that is how they evolved. We can mimic that by just adding trees into the system. Not necessarily growing our vines up them, but we can interplant and also provide a little bit of protection against climate. It’s challenging, because we have to take a new look at how our trellising systems work. Some vineyards would be really challenged to do that without some redesign, but I think we know we need to have more diversity on every farm. A system will always move towards greater complexity for its own resilience and its own stability. We need to think like an ecosystem. We need to think that we can’t possibly have enough diversity.

A system will always move towards greater complexity for its own resilience and its own stability. We need to think like an ecosystem. We need to think that we can’t possibly have enough diversity.

Mimi Casteel, Owner, Hope Well Wines.

ARENI

I’m from Burgundy and my parents had vineyards there. In some of the vineyards, we had walnut trees. Walnut trees were kind of terrible for us, as all the vines around them couldn’t grow. There was no growth underneath them. So I suppose not all trees are suitable?  

Mimi Casteel

I think that we are often tempted to jump into something without thinking through it systematically. To your point, walnuts in particular produce allelopathic compounds: they release compounds into the soil, making it difficult for any plant to get established.  

My family’s estate was previously a walnut orchard. Those compounds can linger in the soil too. The husk of a walnut is black on the inside, and all those really bitter tannins are the same compounds that walnut trees are putting out through their roots. They do that because walnut trees grow very slowly and they need a less competitive environment. So not every tree is going to be appropriate.

Just start by cover cropping, covering the soil, adding some diversity, and then maybe starting to bring in some shrubs, because if you go straight to trees, it can be very difficult to get them established within a vineyard system. And then you have to know why you’re doing it too.

And then we can talk about bringing back a tree layer, if that was appropriate for your ecosystem to begin with. If you removed a bunch of trees in order to plant your vineyard, you should probably put some of those back eventually.

ARENI

I’d like to go back to those two words agroforestry and regenerative viticulture, because in some circles I’ve heard them being used interchangeably. How would you explain those two notions?

Mimi Casteel

Agroforestry, at least the way I think about it, fits in as a category of regenerative agriculture, where you are really trying to produce food within an ecosystem that would be appropriate for the place. A part of agroforestry implies there is going to be a tree layer. The practice of agroforestry often has either some type of crop being grown under a tree canopy, or the crop is actually a tree product. And this gets into one of the tenets of regenerative agriculture, which is farms should be diverse too. But agroforestry very specifically implies that the tree component is part of the agriculture that you’re doing. And that’s not appropriate in every system.

ARENI

When I was growing up with my parents, there was nothing of that kind. And then suddenly we had organic and then we had sustainable. That was even better than organic because it was for social, environmental, and financial. And now we’ve got regenerative, which is not just sustain everything, but actually regenerate and improve.

If regenerative trumps sustainability, can we imagine something that would trump regenerative?

Mimi Casteel

It’s such a loaded question because it comes down to words and how we use them and the meaning behind. To me, regenerative implies that you will never hammer in that last nail. You will never achieve a particular goal. You will always be trying to improve what you’re doing and leaving more behind.

You are constantly trying to rebuild that bank and build it ever bigger, because that is how we will sustain it in perpetuity, as opposed to just maintaining a status quo and a vacuum. We will be able to grow exponentially because one of the things that nature does when it’s allowed to is create infinity in a finite space, and that’s what we are trying to accomplish.

To me, regenerative implies that you will never hammer in that last nail. You will never achieve a particular goal. You will always be trying to improve what you’re doing and leaving more behind.

Mimi Casteel, Owner, Hope Well Wines

ARENI

Many people are inclined to believe that this vision of agriculture is very romantic or poetic, or at best naive and slightly crazy. But far from being a romantic, you actually apply quite rigorous scientific method. Could you share some data and examples with us?

Mimi Casteel

When we think about climate change and, and how climate change is threatening and destabilizing most of our agricultural systems, it’s related to temperatures first and foremost, and water availability. The reason ecosystems move towards complexity is because in that complexity is a built-in buffering system. Every 1% of organic matter in the soil can hold 18,000-20,000 gallons/ 680-750 hl of water. It is a very significant number. And most of our agricultural soils have lost between 70% and 85% of their soil organic matter.

Plants make the biological component of soil and the living organisms that they feed with their photosynthetic products. They create organic matter by living and dying. They break down rock minerals into organic compounds that plants can use. And that organic matter is where most of our potentially sequestered carbon can live temporarily. Our plants also need organic matter to be able to grow appropriately and get the things that they need from the soil. So first and foremost, the more organic matter you have, the more water you can keep in your soil. That also requires thinking about things like the fact that ploughed soil that has been turned over cannot store carbon. There’s no potential to store carbon.

And a lot of people talk about plowing and defend that practice because their plants need the water and they don’t want other vegetation competing. But if you have a diversity of life that use of water becomes cooperative instead of competitive.

When we do things like irrigate or plow so that our plants can have water, that’s a one-time injection. But when the plant is able to get the water in the soil when it needs it, then a full day of efficient photosynthesis can take place. Becoming a buffering system for water also directly affects the temperature: every gram of water can hold 590 calories of heat.

We had some of hottest and driest seasons here, and in June 2021 we had several days in a row above 115 F/46 C. I was taking soil and canopy temperature in my vineyard and in the neighboring vineyards and we measured temperatures in these vineyards that were close to 180F/82 C, so of course temperatures that are very inhospitable for photosynthesis. And we were 30 to 40F/ 1,1 to 4,4 C cooler than that, both at the ground level and at canopy level, because transpiration was still possible and notably the grass plant transpiration. So the humidity of this environment allowed us to walk through that period pretty simply, and we didn’t suffer any damage nor loss.

When we think about climate change and, and how climate change is threatening and destabilizing most of our agricultural systems, it’s related to temperatures first and foremost, and water availability. The reason ecosystems move towards complexity is because in that complexity is a built-in buffering system. Every 1% of organic matter in the soil can hold 18,000-20,000 gallons/ 680-750 hl of water. And most of our agricultural soils have lost between 70% and 85% of their soil organic matter.

Mimi Casteel, Hope Well Wines

ARENI

How does the carbon that you store in the ground affect your capacity for holding water?

Mimi Casteel

Carbon is a building block of life for a reason. And that is because it is nonmetallic and tetravalent. That means it can form four individual bonds. Carbon, when it’s brought into the soil, has all of these bonding sites. Water is a polar molecule and loves to hold on to carbon. Just by virtue of the structure of carbon, it is able to bond to water.

Carbon likes the oxygen and nitrogen and all of those things, and creates these almost hive- like matrices in the soil. All the magic happens in the spaces in between, because you’re able to hold oxygen, you’re able to hold water, you’re able to hold ever more mineral nutrients. The water component cannot be underestimated because if you think about the thermal capacity of water, it can store so much heat as energy. We can actually mitigate temperature with water-holding capacity in our soils.

ARENI

Is that the same for cold temperature? Frost and Burgundy – could they be reduced through more carbon and more water in the ground?

Mimi Casteel

The thermal capacity of water is pretty unparalleled. It has such a unique molecular structure and so much energy can be stored in those bonds that when the water’s in the ground, it has a buffering effect. It can bring you closer to what I would call a neutral temperature. Another tenet of regenerative practices is to really push biodiversity. And the more life you have the more of a buffer temperature you have at the substrate level. The more biodiverse and the healthier your soils are, the more buffered you’re going to be in any extreme weather event.

ARENI

One of the biggest challenges that everyone has around the world is access to labour. How does regenerative change the equation? How does it impact the cost?

Mimi Casteel

To me, regenerative implies the whole entire community. And we have worked very hard to remove people from our farming ecosystems, when in fact we should be trending towards a ratio of hands and eyes to land that is more in line with what we hope to get out of that relationship in the future. And that requires that we start elevating the profession of agricultural work to where it really needs to be. This is not drudgery, it’s not unskilled. Really, if we were designing systems that are high functioning, you need to give people the tools to be able to understand the work that they’re doing. We need to treat labor in a different way.

We use a lot of very sterile terminology, especially when it’s a budget item. We talk about labor like it’s fence posts or something like that. I mean, these are human beings. They deserve fully benefited health care, retirement, work environments that are not dangerous, and that’s part of regeneration.

On average we spend 20% to 30% more on labor than more conventionally farmed vineyards. However, that gets offset by a lot of inputs that we don’t pay for. And in places where you have to pay for water, you know, we don’t pay for water – it’s in the soil.

ARENI

And we are talking a lot about bottom line, but what we also sometimes forget is the top line, is that your asset itself is growing in value.

Mimi Casteel

I always like to talk about compounding interest when we talk about the financial. I don’t think about agriculture as a one-generation effort. None of us should. If we expect future generations to be able to use these lands, I think we really can’t appreciate just how much more valuable those lands are going to be compared to people who aren’t willing to do the work. In a lot of places in the world, we’re looking at our last decade or two of being able to farm those soils.

ARENI

Are there any issues or problems that you are currently trying to solve? What’s your priority at the moment?

Mimi Casteel

There are always challenges when you start transitioning a system. For example, in very hot, dry years, if you have just recently introduced full cover that you’re not cultivating, it can challenge your vines, especially if there are younger vines and maybe they don’t have the same kind of permanent storage structure built. Building soil takes time and it takes investment.

We really need to build a lot of support into this effort right now, because there are ways to do a little bit at a time and give your vines the chance to see their way through that transition period.

ARENI

You obviously spend a lot of time in your vineyard. How does the principles of regenerative viticulture impact your wine making? And is your whole ethos reflected in the way you distribute your wines?

Mimi Casteel

The whole idea behind my wine project, is the idea that we use the word terroir as winemakers without ever challenging our own concept of what that is. In my career, I’ve had those wines that stand out so much from their peers that you just know that there’s something more there. What we’ve done in most of our viticultural systems, just in the last 70 to a hundred years is remove all of the ecosystem that actually made something unique possible in a given place, which is terroir.

And what I want to do with the wines at Hopewell is just always be chasing that higher and higher ceiling of a unique expression of place. The strength of a wine is directly related to its potential alcohol, its pH, the redox potential of the wine, the reductive strength of the wine, without a lot of heavy winemaking. And that is very interesting to me. Do the wines get stronger? Do they get better? Do they last longer?

The whole idea behind my wine project, is the idea that we use the word terroir as winemakers without ever challenging our own concept of what that is. I’ve had those wines that stand out so much from their peers that you just know that there’s something more there. What we’ve done in most of our viticultural systems, just in the last 70 to a hundred years is remove all of the ecosystem that actually made something unique possible in a given place, which is terroir.

Mimi Casteel, Owner, Hope Well Wines

I have a lot of concerns about the impact of packaging, transportation, all of those things. And so, I make very little wine and it doesn’t go very many places and those are very targeted places.

I’ve been in the wine industry long enough to know that more boxes do not equal more dollars. If you then have to be spending all your time selling that wine, there are economies of scale there. And that was never the point for me. I grew up in a time when there was an expectation that if you make wine, you have a day job. You do it because you love it, not because you think it’s going to make you a million dollars. The point is  there is a conversation that can happen around wine that isn’t possible for other agricultural products currently.

And I want to use that platform very responsibly and very intentionally to get people to think about their food and where it’s coming from. And wine has some issues because we send it all over the world and it’s really important and it’s a luxury beverage. We’ve got some reconciling to do in terms of pulling that into a sort of a circular vision for what we think wine’s role is in the world, fine wine in particular.


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