The last few years have seen the expression ‘high-altitude vineyards’ bandied about increasingly in wine marketing communications. It’s true that vineyards are pushing up ever higher all over the world, but the term looks set to follow ‘old vines’ and ‘minerality’ to become yet another questionable buzz expression, understood by few and undefined. Just as few people agree on the age of ‘old vines’, there has been only one attempt to define high altitude for vineyards. CERVIM, a Europe-based association that promotes the understanding of mountain viticulture, sets a minimum of 500 metres. The effects of high altitude on growing conditions for vines and how this translates to the eventual wine are variable and depend on a whole host of other factors.
Temperature and altitude
One incontrovertible fact is that average temperature falls as you go up in altitude. A decrease of 0.6°C per 100-m rise seems to be the accepted average taking into account humidity levels – cloud cover, rain, etc – but ignoring wind chill. If you compared a vineyard at a modest 150-m above sea level with one at 650-m, then the latter should be 3°C cooler on average, a significant figure that affects choice of grape variety in particular. However, this simple calculation ignores factors including the aspect of the vineyard and the proximity of mountains, which in turn influence weather factors that affect temperature and thus ripening.
The expressions ‘the snow line’ and ‘the tree line’ exist for a reason. For the purposes of anything that grows (and for practitioners of mountain sports), latitude must go hand in hand with altitude. While average temperature drops the higher the altitude, in theory, the closer to the equator (the lower the latitude) the warmer it gets. But relating latitude to altitude is far from an exact science. To take two common examples, at around 45°N latitude in Europe, 500-m above sea level might seem fairly high for a vineyard and 800-m very high, but in Mendoza, Argentina, at around 32°S latitude, 600-m is low; 1,000-m is considered fairly high and 1,300-m and above very high. Much further north in Argentina’s Salta province, at a latitude of around 26°S, vineyards are from 1,600-m upwards to over 3,000-m.
Further north again is the emerging wine country of Bolivia, where 100% of the vineyards sit between 1,600-m and 3,000-m above sea level.
Consultant winemaker Paul Hobbs, who has worked in Argentina for 25 years and co-owns Viña Cobos, explains that if a high- altitude vineyard is planted on a wide open slope where cold air cannot get trapped, the temperature may actually be warmer than one at a lower altitude in the same area. It is the distance from the mountain and the snow pack that has a big influence, he maintains. The soil is also important. Rockier, fine silt soils derived from the mountains often provide more warmth than sandy soils, he says, and they also provide better drainage and greater amounts of organic matter – desirable for fine, mineral-laden wines. Argentinean winemaker José Galante of Bodegas Salentein explains that 10 years ago, soil was little considered in Mendoza. “Today we are paying most attention to find the best relationship between altitude and soil.”
Choice of grape variety is not always obvious at altitude. In the vineyards of the Upper Rhône Valley in Valais, Switzerland, some south-facing, steep, rocky slopes at altitudes up to 750-m have proved such sun-traps that winegrowers have replaced some of their Pinot Noir with Syrah, giving excellent results. Their Pinot tended to get sunburnt flavours, whereas Syrah, previously thought to be too ‘Mediterranean’ can ripen fully and give peppery Rhône-like expression. In Mendoza, Hobbs explains that most Argentine agronomists used to believe it was too cold for Cabernet or Malbec above 1,200-m, yet more recent higher plantings in the Uco Valley have proved them wrong, with vines up to 1,500-m and experimental vineyards going higher.
In Europe, until recently, determining the feasible limits for vine ripening was based on local lore – Elisabetta Foradori of Azienda Agricola Foradori in Trentino explained that the limit for vine growing was always said to be ‘up to where the chestnut trees grow’. Today studies and trials abound in both Alpine and Andean wine regions.
Low pH and high acidity is the most common feature of high-altitude wines - the result of lower night-time temperatures and higher diurnal temperature differences close to ripening. In hot areas, such as Mendoza, temperatures at altitude might reach just above 30°C in the day, but at night-time they will drop to below 12°C. This diurnal difference of around 20°C means high levels of photosynthesis during the day and low levels of respiration at night. Low respiration allows flavour to be retained as well as acidity. In much cooler areas like the Alpine regions of Europe, there is a risk that the acidity can be too high at high altitude, hence more resistant white varieties are grown, where freshness and delicate floral aromas are desirable.
Changes in the grape
The other common feature at altitude is the high level of polyphenols and thicker grape skins caused by greater sunlight, hence higher ultra-violet (UV) light intensity. In probably the highest Alpine vineyard – the experimental Vigna 1350 in Italy’s Dolomites – oenologist Fabrizio Zardini claims that there is 35% more energy from UV (1,000 watts per square metre compared to 800 watts) at 1,350-m than a kilometre (1,000- m) down the valley. High winds also thicken the skins. This explains the deep colours and high tannins in Argentinean reds, along with, says Hobbs, much blacker fruit characters. In some instances berries and bunches are likely to be considerably smaller than usual. At Mount Sutherland, South Africa’s highest vineyard, situated at 1,500-m in the Western Cape, owner Daniel de Waal has harvested Syrah grape bunches that are half the size of those using the same clone and rootstock grown in coastal conditions.
For whites the extra polyphenols would only be significant in rare skin contact. In Argentina, Hobbs values high-altitude whites as having greater precision and vibrancy and, according to studies done by Bodegas Salentein, Chardonnay flavours move from yellow fruits to apples and pears at altitude. Of the interest in going ever higher in altitude, Salentein’s Galante says: “When the plant is exposed to the most dramatic conditions, it produces more quality.” It’s what we’ve all been taught – the vine needs to struggle for best results.
Over 70 years ago in Europe’s Alpine regions, many vineyards used to be at much higher altitude than today, providing wines for local drinking. They were gradually abandoned due to lessening demand and the simple fact that labour was hard and costly with little return. At the Trentino cooperative La-Vis, oenologist Marco Sartori explained that labour in vineyards averaging 250-m altitude was 200 hours per ha per annum, compared to 600 hours per ha in the steep and stony vineyards of Val di Cembra at around 800-m. These higher-altitude vineyards have been revived in a quest for higher quality and to combat climate change, something that echoes around the world.
In the highest vineyards in the Uco Valley, Hobbs says there is less risk of hail than lower down, but spring frost presents a hazard. Likewise for de Waal in South Africa, the biggest challenge is black (spring) frost although he also notes, “Because of the extreme isolation of this vineyard, the birds and baboons are also problematic. They feast on the sweet ripe fruit.”
Conversely the isolation – a fact for many other extreme high-altitude vineyards – makes it easier to practice organic methods. This was noted by Zardini too, who notes that the higher polyphenols from the greater UV energy provide the plant with greater disease protection.
Perhaps the greatest challenge and cost in planting at high altitude is that it takes longer for a vineyard to become established, with a great risk of loss of vines. It might be up to five years before a reasonable crop level is obtained instead of the normal three. At Vigna 1350, three successive years of unusual conditions after planting, starting with summer drought, followed by an extremely cold winter, a subsequent cool summer and then damaging heavy winter snowfalls meant 50% of vines were lost. But, says Zardini, if the vine survives two years, it is likely to pull through.
Regions of altitude
The highest commercial vineyards in political Europe are on Tenerife in the Spanish-owned Canary Islands. The highest on the mainland are not in the Alps but in Spain, in the Sierra de la Contraviesa Mountains near Granada, Andalucia – the Barranco Oscuro winery has a vineyard at 1,368-m. At 28°N and 37°N latitude respectively, these have very different growing situations to the more prevalent high-altitude Alpine vineyards. Visperterminen near Zermatt in Valais has claimed the highest vineyards in Switzerland at just over 1,000-m, sometimes wrongly stating they are the “highest in Europe”. In the Alps, the Aosta Valley has had the highest vineyards for many years, reaching around 1,200-m. While Trentino is pushing upwards, neighbouring Alto Adige in the Dolomites seems to have the most quality and commercial potential at altitudes above 1000-m, with several experiments ongoing. Results from the Vigna 1350 vineyard, which is supported by Prosecco producers Bisol, may well encourage others.
The warming climate is certainly enticing producers to move up.
Outside Europe, it is South America that still holds the most potential for high altitude. In South Africa, De Waal says that the challenges and hazards have put off many people joining his efforts to plant high in the Sutherland region, but as long as soil and other climatic conditions are taken into account, he sees much potential. In California, despite plantings going ever higher, Paul Hobbs explains that the diurnal temperature differences are simply not that high. For him, “True altitude is in Argentina, [giving wines with] more elegance and more precision.” Without doubt, with its high-altitude vineyards in Mendoza, San Juan and Salta, Argentina has enjoyed the most success so far. Nearby Bolivia is banking on similar success one day, as are vineyards established across the world in the Himalayas. And recently in Chile, high- altitude vineyard projects have started moving up the Andean mountains reaching 1,000-m in the Andean foothills in Colchagua and Maipo, and up to a massive 2,500-m in some extreme vineyards in the Elqui Valley, 700 km to the north. Lovers of freshness in wines will rejoice at these projects.
