Merlot: Part of the Bordeaux Psyche


Merlot today remains the most planted variety in Bordeaux but its dominance is waning somewhat in an ever warming climate. With “freshness” and “structure” often the buzz words defining the best Bordeaux wines of recent warm vintages – the plush richness and suppleness brought by the merlot variety often seems undersold compared to the role of the Cabernets in the blend. Christian Moueix, Director at Petrus (1970-2008), Trotanoy and La Fleur-Petrus; John Kolasa of Chateau Rauzan Segla and Chateau Canon (1997-2015); Maylis Marcenat of Chateau Clos de Sarpe; as well as Pascal Baratie of Chateau Haut-Brion - the First Growth with the highest proportion of merlot in its blend - identify how global warming is affecting merlot and what this means for its long term future in the region. We also discover why merlot became central to Bordeaux’s success and today remains much loved, providing it is grown in the right place and managed correctly.


The merlot vineyards of Saint-Emilion

Managing rising alcohol levels

There is no grape more synonymous with the region of Bordeaux than merlot, playing an extensive role in almost all wines of the region on both the Left and Right Banks. Whilst it plays second fiddle to the cabernet sauvignon dominant wines of Saint-Julien and Pauillac, everywhere else from Pessac to Pomerol it plays a significant role in the blend. But merlot in recent years has become a concern for many in the region. With the rising climatic temperatures in Bordeaux, some vignerons are struggling to manage ever-rising alcohol levels, whilst trying to achieve full phenolic ripeness of the tannins in the skins and seeds. Merlot is an earlier ripening variety than cabernet sauvignon and its sugar levels can increase quickly in hot temperatures, leaving an imbalance between sugar and tannin ripeness. The more steady the temperatures are through the summer, the more chance the sugar levels and phenolic ripeness will reach optimum levels at the same time. In a hot vintage, sugar levels rise too quickly forcing vignerons to pick the grapes before they have had time for the tannins to reach phenolic maturity, afraid that if the sugar levels become too high, there will be a drop in acidity, as well as causing serious problems at fermentation.


The merlot vineyards of Chateau La Mission Haut-Brion

For Pascal Baratie, vineyard manager at Chateau Haut-Brion the higher levels of alcohol have not however proved problematic for them, stating “since the 2000s, there has been a gap between phenolic maturity and technological maturity (measurement of sugar and acidity levels). Today, during the maturity checks in the vineyard before the harvest, when we taste the grapes at 13 degrees potential alcohol, we note that the tannins are still hard… so we need to wait to obtain more supple tannins and greater phenolic maturity. The balance obtained today, is certainly different to pre-2000 levels, but we are fortunate to be on a great terroir, which produces balanced wines, with a good tannic potential even with high alcoholic degrees. The regularity of great vintages of the last 20 years lets us think that the supposed problem of alcoholic degrees is more in the head than in the glass.” However not all Chateaux are fortunate to share the same terroir as Haut-Brion.


The gravel soils of the Medoc where young merlot can struggle

Drought in Bordeaux

Higher alcohols are not the only concern with merlot. Drought is also becoming problematic when trying to plant young merlot vines in Bordeaux, particularly on gravel soils. Merlot requires moisture to grow and whilst the clay-rich soils of Saint-Estephe on the Left Bank and Pomerol and Saint-Emilion on the Right Bank naturally retain moisture; the gravel soils in Margaux, Saint Julien and Pauillac are becoming increasingly dry in the warming climate. John Kolasa states “this is becoming a real problem where there is deep gravel, like in Margaux. Young merlot vines need years of root growth to break through the gravel and reach water reserves below, but in parts of Margaux where the gravel can be up to two metres deep, the roots take longer than three years to break through. Three years is the current allowance for irrigating vines in the region. It is once this irrigation stops that these vines suffer and die. It is one of the reasons you see less merlot being planted in Margaux. If they can’t find a way for young merlot vines to survive in gravel soils, it will undoubtedly lead to a change in style over the coming years.”


Grey rot can be a real threat to the thinner skinned merlot

Merlot's Susceptibility to Disease

Global warming effects are not just an increase in temperatures but an increase in erratic weather episodes, leading to a heightened pressure of rot and mildew – something merlot is much more susceptible to than the cabernet varieties, due to its thinner skin. “Merlot is a wonderful variety but it is more difficult to manage these days” states Maylis Marcenat from Saint-Emilion's Chateau Clos de Sarpe. “In 2018, our merlot suffered a lot from mildew. We lost around 40% of our production mostly on the merlot vines. The cabernet franc has a better resistance.  The weather is more uncertain these days, a lot of rain followed by a very dry season makes it difficult to predict.”


Christian Moueix in the vineyard

Rot is also a concern and certainly nothing new in the region, it plagued the merlot vines of the late sixties and seventies. So much so, that replanting of the variety was in fact banned in Pomerol following the disastrous 1968 vintage. Vignerons were instead strongly encouraged to plant cabernet sauvignon. Christian Moueix recalls, “I remember, of course, the terrible rot of 1968 and the desire of some researchers to find a varietal resistant to rot. I attended many meetings in 1970-1971 and protested against the banning of planting Merlot. It was a violent controversy and, in 1972, I refused to plant those new cabernets sauvignons in Pomerol.”


The Vineyards of Moueix's Chateau Belair-Monange

Moueix’s decision was justified. John Kolasa states following this ”it became very fashionable to grow cabernet sauvignon in the '60s and '70s on the wrong rootstocks!” Kolasa ended up pulling out all the cabernet sauvignon vines planted at Chateau Canon during this time, stating, “the damn things would never ripen”. The early '70s saw a bout of poor vintages for the region largely due to bad weather either just before or during harvest. The cabernet sauvignon at the time was unripe, incredibly green and it was the earlier ripening merlot that became the more reliable source.

Kolasa outlines one theory behind the rot that plagued merlot on the Right Bank at that time. “Much of the Right Bank back then was undeveloped, compared to the bigger estates on the Left Bank. The vineyards were also producing many other fruit and vegetables. When the vineyards were ploughed by horse and cart these fruit trees were not a problem, the horse simply went around the tree, but with the introduction of tractors and machinery, many vignerons simply chopped down the tree. The trouble is they killed the tree but left the roots in the ground. Similarly to roses, if you leave dead roots in the ground they become infected with fungi. These dead roots in the soil came to plague vineyards with rot at that time.” John recalls finding rotting roots all over the vineyards at Chateau Canon. His first year at the property in 1997, he made two separate cuvees, one from vines away from the tree roots and one nearby. “I only had to put my nose in the glass of the two to know which one was which, the wine made by the affected vines smelt terrible. Following that experiment it was so clear to me. I took up all the vines affected. Pulling up old vines is never something one wants to do, knowing that it will takes decades for the new vines to reach maturity, but these vines were so infected I was left with no choice.”


Merlot as a more reliable source of ripe fruit found favour through the '70s and '80s. By the mid '90s, the influence of the American market enamoured by the plush, richness and soft texture the merlot provides in the blend, only saw more plantings of the variety. For Christian Moueix the Americans love affair with merlot stopped in 2005, with the release of the film Sideways which saw the main character famously state, "If anyone orders Merlot, I'm leaving, I am NOT drinking any f**king merlot!”. It is worth noting his favourite wine in the film was Cheval Blanc, a merlot blend! The damaging effects of global warming have only further put merlot in the shadows as the cabernet varieties share the limelight, but these vignerons are confident of its future in Bordeaux.

Merlot still remains essential to the Bordeaux psyche

Christian Moueix states: “Global warming has been positive for Bordeaux as everybody would admit. The rising of alcohol is almost impossible to control since it comes not only from heat and sun but from the level of CO2 in the atmosphere”. For Moueix provided merlot is planted in the right soil he is confident in its prolonged future in the region. “We still replant merlot in Pomerol and Saint-Emilion; this is the varietal best suited to our terroirs. To manage the climate, we have adapted the canopy to avoid the direct impact of sun. This is all we can do at this point unless the addition of water becomes legal.”


Pascal Baratie - Vineyard Manager of Chateau Haut-Brion & Chateau La Mission Haut-Brion - photo copyright Domaine Clarence Dillon

Baratie from Chateau Haut Brion outlines the importance of balance that both the merlot and cabernet varietals still bring to the classic Bordeaux blend. “We do not want to part with merlot because it is satisfactory today even in hot years and for the future we want to keep its current proportion. We have to keep a balanced planting to obtain maturity on plots of merlot and cabernets whatever the weather conditions of the year. From time to time, we have cooler years and it is interesting to have matured merlot, when the cabernet sauvignons are likely to be harder and herbaceous. In 2011, a very dry spring year, Chateau Haut-Brion was made up of only 35% merlot, while in 2012, a more classic climate year, it was made up of 65.5% merlot. Over two successive years, the climatic conditions were different and led us to select a different proportion of grape varieties in the wine. We can see that we cannot do without merlot in one vintage like the other. Merlot brings an interesting juice, as well as sweetness, fine and supple tannins which make it essential. It may be replaceable with another grape, but at the moment we do not have the knowledge.”


The distinct terroir of Saint-Emilion Grand Cru Classe, Chateau Clos de Sarpe

The Importance of Terroir

Despite the risks of rot, drought, mildew and high sugar levels, fantastic merlot continues to be grown in Bordeaux providing the terroir is right. Speaking with these vignerons one thing they all agree on is that the soil remains the most fundamental aspect to its success - in the past, today and in the future. “Merlot grown on clay and limestone soil can still preserve freshness as well as minimal hydric stress in my terroir. So why not use it?" states Maylis Marcenat from Chateau Clos de Sarpe. “The merlot is still an exceptional plant. The sweetness, the complexity is unique. I think in Saint Emilion, and especially on clay and limestone, all the merlot are more creamy, tasty, with a lot of juiciness.“

At Chateau Haut-Brion, Baratie agrees, “We tend to favour merlot on grounds that are relatively well supplied with water and to favour cabernet sauvignon on gravelly soils. But we have plots of merlot on gravelly soils, little supplied with water, which give very great wines every year and we do not plan to change the grape variety on these very qualitative plots. But in addition, we are adapting later ripening and drought-resistant rootstocks.”

Intra-plot vinification, precise technical understanding of viticulture, clonal development, replanting better matched rootstocks, has all helped Bordeaux and merlot in particular, cope with the changing climate. But the art of blending is still vital part of the wines of Bordeaux and today has become an important measure to reduce the alcohol in merlot dominant wines.


Maylis Marcenat from Chateau Clos de Sarpe

Cabernet Franc to the rescue

Many wineries up and down the Medoc are lowering the proportion of merlot in their blends, opting more for cabernet franc. John Kolasa outlines how cabernet franc can effectively lower the overall alcohol level in the blend of a wine. “Blending just 5% of cabernet franc in with merlot can be an effective method of lowering the alcohol, as well as adding freshness. It is something Petrus did with the 2019 vintage. Look at the success of Chateau Figeac in 2019 – a third cabernet franc, a third merlot and a third cabernet Sauvignon. This is a big increase of cabernet franc in the blend and is performing better in the warming climate”.

The Future of Merlot

Despite the difficulties merlot is facing, there seems plenty of ways vignerons in the region are adapting to manage merlot differently in this warmer climate. Marcenat of Clos du Sarpe believes “the way of cultivating must change. Less green harvesting, we no longer need too much concentration in the grapes, we must be careful with the thinning of the canopy. Merlot needs more cover crops, it benefits from keeping as much grass as possible and we must choose the right organic fertiliser. With this in place, merlot has a future”.

For Baratie “The balance of the wines obtained in recent years suits us, thanks to the contribution of merlot, cabernet franc and cabernet sauvignon, so we are not worried about the future of merlot. However, thanks to our clonal selection initiated by Jean-Bernard Delmas, today we choose clones on a different criteria from those desired in the past. We currently favour two criteria: the Total Polyphenol Index (IPT) and yields that are not too low.” No doubt helping to modify concentration of alcohol and adding structural freshness from the higher levels of tannins.

Moueix too sees merlot having a long future ahead in Bordeaux but at the same time would welcome new clones of Merlot that produce less alcohol. “Nevertheless,” states Christian, ”I dare to compare it to a vaccine : it would need a lot of experiments before taking the risk of replacing the present clones which produce wonderful wines.”

Perhaps the biggest threat for the future of merlot therefore comes not from the clay-rich soils of the Right Bank but from the gravel rich soils of the Medoc, where it remains a minority in the blend, but nevertheless an important element to the profile of these wines. If a solution cannot be found for growing young merlot vines on gravel soil, will we see alternatives varieties in the assemblage and a change in style?


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