Chateau Cheval Blanc, Bordeaux

In September 2024 we had the privilege of visiting Chateau Cheval Blanc in Bordeaux to look at the regenerative practices (especially agroforestry) being implemented in their vineyards. We had the pleasure of spending several hours with Juliette Coombe in the vines, learning the practicalities of agroforestry, cover crops, variation in planting material, animal integration and functional biodiversity.

During this time we also gained an insight into the emphasis Cheval Blanc places on duty. Duty to trial solutions that both adapt to and mitigate climate change, whilst restoring biodiversity. Why do they do it? Because they can, and therefore they should. And they don’t claim to have all the answers. In fact, they emphasise that they definitely don’t have all the answers. That’s why they are experimenting.

Agroecology manifesto

Yes, you read that correctly. Cheval Blanc has a manifesto. Entitled ‘Agroecology at Cheval Blanc’, it details the same practices we at the RVF think are important in regenerative viticulture. It’s accompanied by beautiful illustrations. It’s a short, succinct thing of beauty. You would expect nothing less, as its contributors include visionaries like Alain Canet, Konrad Schreiber and Marc-Andreé Selosse.

When I told people I was visiting Cheval Blanc, of course everyone asked if I would get to try the wine (as working for a charity doesn’t normally fill the bank account sufficiently to buy iconic Bordeaux wine). Now, we know it is ultimately all about producing staggeringly beautiful wine. But I’m a bit weird. I was much more excited to get my hands on a physical copy of the manifesto. Reading it is a joy. If you are interested to find out what this agroecological regen thing is all about, read the manifesto online (though sadly it’s not quite so tactile in pdf form).

Agroforestry

Cheval Blanc has been implementing a programme of agroforestry within the vineyards. At the start of the experiment (and it is an experiment – they felt it would be wrong to wait until someone else had proven the case), they decided to trial trees throughout the vineyards. They could have done just one block and waited for the results before expanding the trial throughout the estate. However, they felt there was an urgency to help mitigate and adapt to climate change, and to restore biodiversity. Therefore they have planted 1500 trees across 30% of Cheval Blanc vineyards, 50% of ?? and 100% of the small 5 ha white wine vineyard Le Petit Cheval.

Prior to planting, agroforestry supremo Alain Canet shared the plans with all staff, to ensure they understood why the trees were being planted. Attaining staff buy-in is crucial because there is of course an effect on vineyard management practices. If your job has been made slightly harder – or just different – you need to know what the benefits are if you’re not going to be frustrated!

Patterns of tree planting

The planting has been done in different patterns. Similarly to Chateau Palmer, most trees have been planted to replace individual vines dotted along rows, every 8th row. Tall end posts clearly indicate these rows to tractor drivers to aid management. However, they have also created a small grove/copse of trees when replanting a block. Juliette feels this is a really good solution as it is both easier to manage and the best for biodiversity, as it has different levels of vegetation. She also feels it could be a good compromise for other producers who use machine harvesting, as it is not possible to machine harvest rows with trees planted in them.

Types of trees

Both woodland trees and fruit trees have been planted. The fruit trees are good for produce, but their lifespans are much shorter than the 100 years expected from a Cheval Blanc grapevine. Peaches, apricots, apples, pears and plums were trialled initially. Peaches proved too fragile. The apricots do not suit the soil type. Apples, pears and plums are perfect.

Age of trees

Hoping to get a head start, initially 4 year old trees were trialled. However, they soon discovered that this was not the best solution as the trees suffered transplant shock when removed from their comfortable nursery conditions and placed in the open vineyard, with sunburn, wind, frost, etc. A later planting of one year old trees has almost caught up with these early 4 year old plantings.

Young trees are also preferable as they can be trained to the correct shape without having to make large pruning cuts into older wood.

Training system

To enable machinery to pass along the rows, the trees are trained with the first branches above the top foliage wire and with all branches in line with the row, i.e. no branches are allowed to protrude into the row. The woodland trees will be pollarded, with prunings from all the trees put on the ground and shredded along with vine prunings to increase organic matter.

Monitoring outcomes

Juliette is working with Marc-Andre Selosse and using interns to monitor:

• Water status: this is the big question… will the trees provide too much competition for water?
• Harvest yields and composition: indicators are being measured each year at the same locations in the vineyard
• Fungal diseases: they are being hypervigilant to the appearance of decomposition fungi as they do not wish to introduce trunk disease. Whilst they are clearly working to increase mycorrhizal fungi in the soil, they will remove any trees with evidence of disease
• Soil biology: they are most interested in what is happening underground with fungi and bacteria. Soil samples were taken before planting the trees to create baseline data. Intermediate sampling has been done this year but results were not yet in when we visited. Researchers anticipate that changes around the vicinity of the trees will take place rapidly, but it will take longer to see a difference further away from the trees. Another 5 years is needed to see a real difference – we’re talking long timescales here!

These are not (yet) scientific research trials. If and when they have evidence of interesting outcomes, they will start working with researchers.

And the most amazing thing? If the experiment turns out to not be working… that’s fine, they’ll just pull out the trees. They just don’t want to wait 10 years to find out first.

What about the appellation? Are they happy? Yes, they are very supportive of their work as it will encourage other producers to plant trees.

Cover crops

The mindset change…

15 years ago Cheval Blanc used cultivation to control the vineyard floor. They started to cultivate less and realised that the ‘weeds’ were not a problem. So in 2020 they started using cover crops to protect the soil.

What do they sow and why?

When we visited in September 2024, there was actively growing clover and the remnants of mulch from the cover crops that had been growing during the season. This season had been a mix of 10 species, 60% cereals and 40% legumes. This is to provide the correct level of nitrogen that the vines need and to produce a mulch to cover the soil.

Some blocks still use cultivation, enabling them to compare the soil under the 2 regimes.

• Soil temperatures: in the very hot 2022 growing season the cover crops made a real impact to soil temperatures
• Organic matter: to date there has not been a difference in organic matter but at the time of our visit they were awaiting the results of some sampling
• Earthworm counts: there has been an increase between earthworm counts of 2020 vs today and also between cover cropped and non-cover cropped soil. Sampling is done using mustard sampling (this is a widespread French technique that involves spreading mustard over the soil and counting the earthworms that appear)

How do they sow?

Cover crop seeds are sown annually. A few weeks after harvest the ground is worked very superficially. Two rows are seeded simultaneously with the straddle tractor. The drill opens up a slot in the soil, deposits the seed and closes the slot up again. This presents difficulties with sowing large and small seeds at the same time but they have worked with a cereals company to adapt the technology to viticulture.

How are they managed?

The cover crops are rolled to create a mat of cover. This is one of the areas of experimentation that turned out differently to that anticipated. One rolling is not sufficient as the plants re-grow. They need to roll it 2 or 3 times to stop it growing back.

(Bio)diversity to avoid monocultures and reduce chemical inputs

Cheval Blanc is unusual in Bordeaux in that they have a high percentage of Cabernet Franc. They have done much work to preserve old clones to increase diversity of planting material and therefore increase resilience.

The cover crops and trees increase diversity and biodiversity, helping with insect pests. They decided not to plant cherry trees to avoid spotted wing drosophila (SWD) which they had a problem with in 2017 but not since. Sexual confusion has been successful against ver de la grappe (European grape moth Lobesia botrana) for 20 years. It is mandatory to spray against Flavescence doree every 4 years.

Fungal diseases are an issue in this maritime climate. Cheval Blanc has not gone for organic certification as they do not want to add more copper to the soil. They therefore practise a regime of spraying the minimum amount of products with good efficacy, minimising workers’ exposure, diesel use and water use. No herbicides are used.

To increase polyculture, a large area has been replanted for market gardens and rearing pigs, sheep and chickens – we are talking eye wateringly expensive St Emilion appellation land here! All staff receive produce and it is also used by the chefs. The sheep are put into the vineyards once the leaves have started to senesce after harvest. This provides fertiliser. The pigs live in rather glamorous repurposed foudres.

We were there for harvest, which is of course an exciting time at any wine estate. It was really fascinating to watch the berry sorting process, but I’ll stick to writing about viticulture, rather than going off on that whole tangent…

What was lovely at Cheval Blanc was the way all the workers sit together for lunch, from pickers and press operatives all the way up to Pierre Olivier Clouet. The food is from the estate. and they all get to enjoy a glass of Cheval Blanc wine with their lunch. As did we (yes, you’ll be pleased to read I did get to try the wine). This isn’t restricted to harvest time though. There might not be three course meals laid on throughout the year but all the staff come together to eat their lunch. Now that’s got to be better than eating a sandwich at your desk…