The Grape Story Part 2 - What is Terroir?
A dozen growers will give a dozen different definitions for terroir. Theoretically, it’s the idea of grapes coming from a region or vineyard with a specific sense of place, which couldn’t be replicated.
There are several factors which constitute terroir, and many literary pieces and educational materials have been devoted to the elaboration of the idea. However, fundamentally, there are 5 key concepts which must be considered when defining terroir.
The climate of a site refers to its annual weather patterns over a significant period of time. Weather patterns change year-on-year, but the overall climate remains relatively unchanged. A famous (unconfirmed) Mark Twain quote reads: “climate is what we expect; weather is what we get.”
Parameters by which climates are assessed include – average rainfall, length of the growing season (the number of days between bud burst and harvest), and continentality (the difference between the average temperature of the hottest and coldest month). The climate of a given site or region will largely influence the grape varieties which can be successfully ripened, and the styles of wines produced.
There are several different climatic categories, of which only three or four are of interest to the modern viticulturist.
A Continental climate is characterised by bitterly cold winters and hot summers, with a short to medium growing season. Winter runs well into February and harvests usually begin at the end of September. Rainfall is usually moderate (500-650mm), most of which occurs outside the growing season. Burgundy, Canada’s Niagara Peninsular and Tasmania all fall within this category, which is known for crisp whites and lean reds from varieties such as Chardonnay, Riesling, Gewürztraminer and Pinot Noir.
Maritime climates are characterised by mild winters and warm summers, with a medium to long growing season. Their temperatures are usually moderated by large bodies of moving water, such as the Gironde River in Bordeaux. The high rainfall (900mm+) usually occurs in and around the autumn period, bringing with it an increased risk of fungal disease. Merlot, Cabernet Sauvignon and Sauvignon Blanc typically dominate this class – think Bordeaux varietals.
Mediterranean climates are characterised by very hot summers, mild winters and low rainfall (below 500mm). Most of California’s Central Valley, Languedoc-Roussillon, Provence and parts of Tuscany fall within this category, which is most suitable to heat loving varieties such as Zinfandel, Grenache, Viognier, Marsanne and Roussanne.
With the climate of a region or site being known, the weather refers to the actual daily, weekly and monthly conditions. We know to expect cold winters from continental climates and high rainfall from maritime climates, but what actually pans out is what makes up the weather.
The weather conditions of a given year determine the actual quality of the fruit grown and wine made. This is why certain vintages are more prized than others, Bordeaux 2009 for example. A hot and relatively dry year in a maritime climate can produce some truly stunning wines, while a cool and wet autumn in a continental climate will produce some overly acidic wines as grapes struggle to reach adequate ripeness levels.
Altitude refers to location with respect to sea-level. For every altitude increase of 100m there is a 0.5-0.6°C reduction in temperature. This is often a key consideration for Mediterranean climates, where cooler sites are prized for their ability to slow down the ripening process, thus aiding in the development of complex flavours, and for their acid retention capabilities. Some of Argentina’s best wines come from regions such as Tupungato, which sits at 3250ft (999m) altitude – which roughly translates to a 5-6°C drop in temperature compared to the valley floors.
Aspect simply refers to the angle of the slope – both the gradient of inclination and the direction of the slope are of interest to the grower. The sun rises from the east and sets in the west, therefore east facing slopes in the Northern Hemisphere are particularly prized, as they capture most of the morning sun. While this is advantageous in a continental climate where sunlight and warmth is met with a toast to Dionysus, it might prove problematic in a Mediterranean climate where cooler growing conditions are preferred, as they slow down the ripening process and help control the tendency for high grape sugar content ergo, highly alcoholic wines.
The angle of the slope not only determines how well the site drains, but also the extent to which mechanisation might be possible. While many growers wax lyrical about the significant benefits of hand harvesting, the reality is that this can be up to 10 times more expensive than mechanical harvesting. However, slopes with a gradient in excess of 35-40% generally prove to be problematic for vineyard machinery.
Soils vary in texture, composition, moisture content, nutrient levels and water retention capacity. Gravel soils are generally lauded for their free draining and heat retention capabilities. These free-draining soils force the vines to grow deep roots, which is beneficial to their longevity and ability to cope with adverse growing conditions. Gravel soils also dry up quicker after precipitation, thereby minimising the risk of fungal diseases which can arise from damp growing conditions. Chalky subsoil can also be beneficial as chalk can soak up excess rain, acting as an underground water reserve for the vines.
The concept of terroir isn’t simply the climate, weather, rainfall, aspect or type of soil which a region or site possesses, but how these individual components advantageously work together to produce better quality grapes and ultimately, better wine. The hill of Corton in Beaune offers a unique terroir, in that it is located in the heart of a continental climate region (Burgundy), with mainly clay and limestone soils, and the south facing aspect of the slope is able to capture most of the morning sun which aids ripening. However, at 200-350m altitude, the ripening processes are slow and meticulous, allowing for the formation of complex flavours and aromas. Combined with favourable weather conditions over a given growing season, this terroir can produce truly exceptional and distinctive wines.