Welcome to the first part of our series Terroir & the Chemistry of Wine. Across nine articles we follow the wine from the vineyard to the bottle, and we begin where everything starts: in the soil, in the climate and in the landscape. Terroir is a word that gets used a great deal, but is rarely explained properly. Let us do that here, calmly and thoroughly.
Think of this part as the foundation. When we later talk about acids, phenols and aroma compounds, we keep returning to the framework that nature sets in the vineyard. Understand it, and you understand why two vines of the same grape can give wildly different wines.
Hvad du lærer
- How terroir is an interplay between soil, climate and location, not a single factor
- How soil, drainage and nutrition shape the vine's growth and ripening
- What role climate, microclimate and sunlight play in grape ripening
- How to distinguish what terroir provides from the choices people make in the vineyard and cellar
What terroir covers
Terroir is not a single condition, but the sum of the interconnected environmental and geographical factors that influence how the grapes ripen, what quality they attain, and thereby the character of the wine. It is about location, climate, the weather of the vintage, the vineyard's orientation towards the sun and the composition of the soil, all working together.
The geographical starting point is already part of the picture. The vast majority of the world's wine production lies between the 30th and 50th parallels in both hemispheres, where the average annual temperature typically falls between 10°C and 20°C. Within that belt the finer differences begin to emerge, and those are what terroir is about.
An important part of terroir is the vintage. The weather varies from year to year and can deviate markedly from the region's general climate. A single year's weather can lift a harvest or challenge it, and that is precisely why the wine year can never be reduced to an average.
Soil, drainage and nutrition
The soil does two things at once: it gives the vine a foothold and nutrition, and it controls how much water the roots have access to. The topsoil carries the majority of the root network and supply system, while the subsoil affects drainage and access to minerals as the roots reach deeper.
A well-suited vineyard soil often has thin topsoil, an easily permeable and well-drained subsoil, and a good capacity to retain moisture. The point is balance. The soil should avoid waterlogging, yet still give the roots access to moisture in dry periods. A controlled water deficit can actually be an advantage: it inhibits cell division and cell expansion, so the berries become smaller, which concentrates the contents.
Warm and cold soils
The soil's ability to absorb and retain heat has a direct bearing on ripening. Warm soils such as gravel, sand and loam speed up ripening, while cold soils such as clay slow it down. Limestone sits in between. The chemistry of the soil also comes into play: alkaline soils with high pH, such as limestone, promote acidity in the grape juice, while acidic soils pull the acidity down. We return to this in The Acids and pH of Wine.
The nutrients
The vine needs a handful of elements to function. Nitrogen drives green growth, phosphate supports root development and early ripening, and potassium plays into metabolism and next year's vigour. Iron and magnesium are central to photosynthesis and chlorophyll, while calcium contributes to the nutrition of the roots and to the structure of the soil. Different grape varieties thrive best in different soil types, precisely because their mineral needs and natural vigour vary.
Climate, microclimate and sunlight
Climate sets the overall framework for whether a grape can ripen at all. The vine requires an annual mean temperature of at least 10°C to produce grapes suitable for winemaking. The ideal lies around 14 to 15°C, with a summer average no lower than 19°C and a winter minimum around -1°C.
Ripening also requires sufficient heat accumulation over the growing season as well as light. As a rule of thumb, around 1,300 hours of sunshine per season is a minimum, while 1,500 hours is preferable. And water is needed too, typically in the order of 68 centimetres of rainfall per year, preferably concentrated in spring and winter with a little summer rain.
Frost, friend and foe
Frost is not unequivocally negative. Winter frost can do good by hardening the wood and killing pests. But frost at the wrong times, at budbreak and flowering, can damage the harvest severely. Flowering is the most vulnerable phase, where frost, hail, rain, wind and temperature swings can, in the worst case, destroy an entire harvest.
Microclimate
Microclimate is the climate of the very local, down to the individual plot and even to the vine's immediate surroundings. Here the details carry weight. In cooler regions, south-facing slopes are preferred in the northern hemisphere (north-facing in the southern), because they catch more sun. Proximity to a river or lake can also help: the water reflects light and acts as a heat reservoir, which lowers the risk of frost.
Geology and location
The shape of the landscape is an underrated part of terroir. A slope gives a steeper angle to the sun and thereby better use of the light, and it drains naturally, so water does not sit still around the roots.
Altitude pulls in the opposite direction of heat. For every 100 metres of elevation, the ripening period is extended by about 10 to 15 days, and acidity rises. This is one of the reasons that wines from higher-lying vineyards often seem fresher and tighter in acidity. Together, slope, orientation, altitude and proximity to water draw the fingerprint that the individual site sets on the grape.
Terroir vs. the human hand
It is tempting to attribute everything in the glass to terroir. But a large part of a wine's character is the result of human choices, both in the vineyard and in the cellar. The growing method actually influences quality more than the grape variety alone.
In the vineyard, training and pruning systems control how the vine is exposed to the soil's heat, to sunlight and to frost near the ground. Pruning reduces the amount of fruit to raise quality, and the timing of the harvest determines the balance between sugar, acid, colour and tannin: white wine often benefits from the higher acidity of earlier-harvested grapes, while red wine typically requires lower acidity and more colour and tannin from a later harvest.
In the cellar, vinification and growing technique can stretch or concentrate the grape's varietal character independently of terroir. The point is not that one is genuine and the other false. The point is that you, as someone interested in wine, learn to hear the difference between what the place provides and what people shape. That is precisely the distinction we build on through the rest of the series.
Kort fortalt
- Terroir is the interplay between soil, climate, location and vintage, not a single factor
- The soil shapes the vine through drainage, heat absorption, pH and nutrition, and a certain balance between moisture and drought stress can concentrate the berries
- Climate sets the broad framework, while microclimate, slope, sun orientation and altitude fine-tune ripening
- Frost can both help and harm, depending on when in the year it strikes
- A large part of a wine's expression stems from human choices in the vineyard and cellar, and distinguishing that from terroir is a key skill
Ofte stillede spørgsmål
Is terroir the same as soil?
No. The soil is an important part of terroir, but terroir also covers climate, microclimate, location, slope, altitude and the weather of the vintage. It is the interplay between them, not the soil alone, that shapes the grape.
Why do higher-lying vineyards often give fresher wines?
Because temperature falls with altitude. For every 100 metres, ripening is extended by about 10 to 15 days, and acidity rises. This typically gives grapes with more preserved freshness.
Klar til næste skridt?
Now that you have the foundation in place, it is natural to dive into the chemistry that terroir sets in motion. In the next part, The Acids and pH of Wine, we take a closer look at how climate and soil are translated into acidity in the glass, and why pH matters so much for both taste and longevity.
Do bring that curiosity along when you explore our selection. Notice how location and cultivation are described, and try to taste the difference. And then remember the most important thing: the right pairing is the wine you like, with the food you like. The rest is immersion, and we look forward to sharing it with you.