This document discusses the concept of terroir and the factors that contribute to terroir. It states that terroir is influenced by an interaction of climate, soil, vines and human practices. Experience from old world wine regions shows that choosing the right grape varieties suited to local climatic conditions is important for expressing terroir. Soil type, slope, drainage and vine training techniques can also impact the microclimate experienced by the vines and the quality of the resulting wine. The document advocates for cool climate viticulture which allows grapes to fully ripen late in the season, improving aromatic expression.

2. GRAPES
ARE
TERROIR
TONG N° 2
–03 –
— By Kees van Leeuwen, France —

3. The best expression of terroir is when grapes
are fully ripe by the end of the growing season.
Overly-vigorous vines don’t produce high-
quality red wines. The best conditions for these
are met on shallow or stony soils in moderately
dry climates, where there is neither too much
water or nitrogen. In the case of high-quality
white wines, you need regular if not too much
water and nitrogen. But in order to have great
terroir, the socio-economic conditions must
be right too.
Terroir is an interactive ecosystem involv-
ing climate, soil and vines. There is no ideal
climate for fine wines in terms of temperature,
rainfall or solar radiation, and there is no ideal
soil in terms of depth, or its content in pebbles,
clay, lime or minerals, simply because these
environmental factors only make sense when
they interact with the vine.
History, socio-economics and viticultural
and oenological techniques are also essential to
the understanding of terroir. Socio-economic
history may help us understand why a given
vineyard has emerged and prospered in a par-
ticular site, and mastery of viticultural and
oenological practices is indispensable for
making the best of the natural environment.
The human factor
It goes without saying there would be no vine-
yards without human intervention. Vines, like
olive trees, don’t need much water or minerals,
so farmers have traditionally reserved their
richer soils for cereals and grazing, planting
their vines on shallow or stony soils, or on
steep slopes. None of the currently cultivated
varieties of Vitis vinifera were ever to be found
growing in the wild – grapevine varieties were
developed to produce high-quality wines.
Vineyards have always developed where
the socio-economic conditions were favourable
– close to towns and their potential consumers,
near harbours or navigable rivers. Where the
natural environment was conducive to growing
quality wines, the vineyards survived; else-
where, they did not.
Vineyards naturally developed outside
Paris – always a centre for wine consumption.
In 1820, the region was producing up to 4.8
million hectolitres of wine on 24,000 ha,
although climatic conditions were far from
ideal. With the opening of the Paris-Lyon-
Marseille railway in the second half of the
19th century, when transport was no longer
–04 –
TONG N° 2
We viticulturists care deeply about terroir because it’s
what connects a wine’s taste and smell to where the
grapes were grown. Terroir goes a long way to explaining
differences in the quality and styles of wines, and yet it
is tricky to approach scientifically because so many
interacting factors are involved, including climate, soil,
cultivar and human practices.
Dutchman Kees van Leeuwen is Professor of
Viticulture at the University of Bordeaux.
He is among the world’s leading experts on
viticultural issues, and particularly on the
terroirs of Bordeaux. He is also technical
consultant at the prestigious Château Cheval
Blanc in Saint-Emilion, where he lives.

4. an issue, the trade moved to the much more
favourable climate of southern France.
In the Middle Ages, two vineyards close
to La Rochelle and Bordeaux did a brisk trade
with England and Holland. But the soils at
La Rochelle were poor for wine-growing, and
were abandoned with the decline of the port;
Bordeaux survived, despite its port’s decline,
because the soil, climate and cultivars used
around the city were ideal for the production
of high-quality wines.
Still today, new vineyards develop where
the socio-economic context is right. The Pic
Saint-Loup area in Languedoc-Roussillon is an
attractive site for investors – the countryside is
beautiful, Montpellier and the Mediterranean
are close. In Australia, early settlers bringing
vine cuttings via Sydney introduced wine-
growing to the Hunter Valley, despite its inaus-
piciously humid climate. Later, wine-growing
moved to more favourable sites, although the
vineyards in the Barossa and Yarra Valleys
developed principally because they were close
to Adelaide and Melbourne.
Bordeaux started to produce “wines of
origin” because of its trade with England.
Until the 17th century, Bordeaux wines were
named after the local parish. Some origins were
known to produce better wines than others,
and their wines were priced accordingly.
In the 17th century, Arnaud de Pontac of
Château Haut-Brion started to sell his wines
under his estate’s name. Convinced that his
wines were superior to other Pessac wines,
he raised their prices accordingly.
When de Pontac’s son opened a tavern in
London, Haut-Brion became an instant hit and,
in 1677, the English philosopher John Locke
visited Haut-Brion, later writing: “The vine de
Pontac, so much esteemed in England, grown
on a rising open to the West, in a white sand
mixed with a little gravel, which one would
think bear nothing; but there is so much a par-
ticularity in the soil, that at Mr Pontac’s near
Bordeaux the merchants assured me that the
wine growing in the very next vineyards,
where there was only a ditch between, and the
soil, to appearance, perfectly the same, was by
no means so good.” Thus, as early as the second
half of the 17th century, it was known that soil
explained the quality of Bordeaux wines.
Inspired by the example of Château Haut-
Brion, several other rich Bordeaux merchants
of the 17th and 18th centuries created large
estates. Some of today’s most famous Médoc
estates were among the first to be planted;
people had enough empirical knowledge to
select the best sites. Qualitative differences –
which served as the basis for the 1855 classifi-
cation – led to a sophisticated hierarchy in
sales prices. Although the classification didn’t
evoke such terroir-related factors as climate
and soil, the wines from the Médoc châteaux
can be considered “terroir wines.” These
châteaux produce wines from their own
grapes, in vineyards with soils that haven’t
budged over years.
Wine production today distinguishes
“terroir” from “branded” wines. Terroir wines
(which include estate and single-vineyard
wines) are influenced by the climate and soil
of a particular location. Their volume can’t
be increased, which is why the more famous
terroir wines are good speculative investments.
Branded wines, on the other hand, are pro-
duced by blending wine or grapes from larger
areas and a variety of sources. They are the result
of oenological processes and blending, and
their volume can be increased to meet demand.
Terroir wines have always had excellent
traceability – an important issue in the agro-
business. Even three centuries ago, a consumer
who enjoyed a bottle of Lafite could visit the
vines that had produced the fruit, know when
the wine was made and bottled and meet the
people involved in its production.
A vine of many climates
A perennial plant, the vine adapts easily to
different climatic conditions. Vitis vinifera,
the main cultivated species used for quality
wines, can survive temperatures as low as
-15ºC to -20°C (depending on the cultivar).
With cultivars, the temperatures needed for
grapes to ripen fully vary considerably.
Most early ripening cultivars require at
least 1,200 degree days base of 10ºC – a limi-
tation on vine cultivation at high latitudes.
In equatorial regions, vine vegetation is contin-
uous and all the reproductive stages take place
simultaneously. Fruit grown under these condi-
tions doesn’t make great wines, although it pro-
duces commendable table wines. The zone best
suited to growing high-quality grapes is between
the 35th and 50th parallel latitude of the Northern
and Southern hemispheres. In some cases, high
altitude compensates for low latitude.
How early berries ripen is determined by
genes that vary from one cultivar to the next.
French researcher Pierre Huglin has calculated
the heat requirements of a wide range of
cultivars. In the ampelographic collection of
Montpellier’s Ecole Nationale Supérieure
d’Agronomie, where several hundred cultivars
are grown in the same vineyard, there can be
–05 –
KEES VAN LEEUWEN

6. a two-month time lag between the ripening of
the earliest and the latest grapes.
In the traditional wine-growing regions of
Europe, growers have used this property to adapt
their vines to local climatic conditions. At high
latitudes, early-ripening grapes produce high-
quality wines. Unripe grapes give green, acidic
wines with low alcohol levels because the fruit
hasn’t accumulated enough sugar. Early ripening
varieties such as Pinot Noir, Chardonnay and
Gewürztraminer are much more appropriate.
At lower latitudes, where the climate is
warmer, grapes ripen early in the summer.
Quick ripening reduces a wine’s aromatic
expression. In 1960, researchers Jean Ribéreau-
Gayon and Emile Peynaud noted that “the best
wines are produced with cultivars that just
achieve ripeness under the local climatic
conditions, as if quick ripening of the grapes
burned the essences that make the finesse
of great wines.”
Growers have accordingly planted late-
ripening varieties such as Grenache and
Mourvèdre at low latitudes in warmer climates.
As a result, in Europe’s traditional wine-growing
regions, grape-picking generally takes place
between September 10 and October 10, despite
huge climatic differences between, for example,
the Mosel in Germany and Alicante in Spain.
This type of viticulture is also called “cool
climate viticulture”, not because the climate is
particularly cool but because the ripening of
the grapes occurs in cool conditions at the end
of the summer or in early autumn.
Originally, New World viticulturists lacked
the experience of Old World growers about
what cultivars to choose for what climatic
conditions. They usually planted early-ripening
varieties in relatively warm conditions. These
varieties were chosen as much for marketing
as for technical reasons (Chardonnay to pro-
duce a white burgundy-style wine, Cabernet
Sauvignon to produce a red Médoc-style
wine). But although the grapes ripened easily
(resulting in high sugar and low organic acid
content), they lacked specific aromas.
Wine-making technology can compensate
for neutrality in grapes, as in the case of most
New World Chardonnay wines. Yeasts produce
highly aromatic esters (e.g. isoamyl acetate,
isobutyl acetate) when alcoholic fermentation
takes place at low temperatures. Lactic bacteria
produce aldehydes and carbonyl compounds
during malolactic fermentation (e.g. diacetyl,
which smells like butter). Fermentation in new
oak gives vanilla aromas.
If the wine-making technology is controlled,
early-ripening varieties in warm climates can
produce good wines, but because the grapes
don’t have a high level of aroma compounds,
they lack terroir expression. These wines often
taste alike, which is why many wine lovers
swear, “Anything but Chardonnay.”
Greater experience is why there is more
cool climate viticulture in the Old than in the
New World and, consequently, more wines
expressing terroir. New World viticulturists
are beginning to seek out cooler areas, such
as California’s Carneros region north of San
Francisco where the cool influence of the bay
is greater than in the Napa Valley, or the coastal
region near Monterrey. In Australia, the rela-
tively cool Yarra Valley (north of Melbourne)
and Western Australia are fast developing
regions. New Zealand Sauvignon Blanc shows
how powerfully aromatic this variety can be
when grown in cool conditions.
Another look at climate
Climatic variability within a wine-growing
region can be described as mesoclimatic vari-
ability. When it is the result of relief (altitude,
aspect, slope), it is called topoclimatic vari-
ability. Topoclimate can be a major terroir factor
in cool regions, where grapes ripen with more
difficulty. The Mosel Valley in Germany, for
instance, can only produce quality wines on
steep, south-facing slopes. In Burgundy, the best
wines are produced in the Côte d’Or, at approx-
imately 300 metres above sea level. In the
higher Hautes-Côtes, it is harder for grapes to
reach complete ripeness. Picking is delayed by
10 days, and wine quality is generally good but
rarely outstanding, despite the fact that this part
of Burgundy has some fine vine-growing soils.
Soil type and canopy management can
affect microclimatic conditions, and can have
a serious impact on a vineyard’s performance.
Dry soils (such as stony soils) warm up faster
than wet soils and induce early ripening.
Night temperatures are cooler close to the
ground, but day temperatures are higher.
When a cultivar has a hard time ripening in
the given climatic conditions (like Cabernet
Sauvignon in the Bordeaux area), low vine
training can improve quality, although it also
increases the vine’s susceptibility to spring frost.
–07 –
KEES VAN LEEUWEN
“Experience explains why there’s more cool climate viti-
culture in the Old World and thus more terroir wines”

7. alkaline limestone soils (Ausone), acidic grav-
elly soils (Lafite-Rothschild), neutral gravelly
soils (Cheval Blanc) and heavy clay soils
(Petrus, Cheval Blanc). It is difficult to equate
the soil map of a given region with a map of
wine-growing quality potential.
It’s all about dosage
The agronomical approach considers the inter-
action between soil and vine. The temperature
in the root zone, and mineral and water sup-
plies, influence the behaviour of the vine and
the quality of the wine.
The research undertaken by Barbeau and
others has demonstrated that vine precocity,
especially at bud-break, is linked to the tem-
perature of the soil in the root zone. It is high
in dry and shallow soils and low in deep,
humid soils. In cool climates, vine precocity
can be an important quality factor, as in the
Loire Valley, where it is difficult to ripen
Cabernet Franc in cool vintages.
Nitrogen is the mineral element that most
influences vine vigour, yield and grape ripen-
ing, and many studies have looked into how
much is needed. Other studies deal with the
depressive effect of cover crops on nitrogen
supply, which goes some way to explaining
the quality-improving effect of this technique
in red wine production. Much less well docu-
mented in scientific literature is the fact that a
vine’s nitrogen uptake is likely to vary consid-
erably according to a particular soil’s content
in organic matter. Soil organic matter turnover
depends on soil temperature, aeration, pH and
moisture content. It is also very much slowed
down by the presence of active limestone. As
a result, one of the components of terroir is
the level of natural soil nitrogen supply to the
vines; the soil types make this highly variable.
Xavier Choné et al. demonstrated that lim-
ited nitrogen supply to the vines due to soil
parameters increases quality in red wines
because it reduces the vine’s vigour and
increases the berry and wine phenols. This is
not true of white wines, where there is a greater
need for vine nitrogen supply to obtain a high
aroma potential in grapes.
To drink or not to drink?
Vine water status depends on climate (rainfall
and potential evapo-transpiration), soil (water
holding capacity) and training system (canopy
architecture and leaf area). Vine water uptake
conditions are key to understanding the effect
of terroir on the quality of the grape, because
–08 –
TONG N° 2
In warm climates, with early-ripening varieties,
high vine training delays the ripening of the
fruit. Soils inducing low vine vigour (for
instance, because of low water/nitrogen avail-
ability) improve light penetration inside the
canopy and on to the fruit zone, which is
essential for growing high-quality fruit.
Rock ’n’ roll
Vines can grow on a huge variety of soils.
In deep, rich soils, they are vigorous and high-
ly productive, although the better wines are
generally produced on poor soils. Soil’s effect
on vine behaviour and grape composition is
complex because it influences both mineral
nutrition and water uptake, but also root depth
and temperature in the root zone. Soils can be
studied from geological, pedological and agro-
nomic perspectives.
Geology deals with rock types and the
dating of sedimentary strata, and acts indi-
rectly on topography. Soil type is also related
to the sort of rock on which it has developed.
In some regions, there is a strong correlation
between geological sediment and the quality of
the wines produced on it. The most commonly
cited example is Chablis. All the famous vine-
yards are planted on Kimmeridgian limestone
and marl, while vineyards on Portlandian lime-
stone produce the less famous Petit Chablis.
The influence of the rock type on the geomor-
phology of the region is undoubtedly crucial.
South- and east-facing slopes are shaped in
the soft Kimmeridgian limestone and marl,
providing good sun exposure and compensat-
ing for the cool climate of the Chablis region.
The harder Portlandian rock is found at higher
altitudes on wind-exposed plateaux, where it
is harder for Chardonnay grapes to fully ripen.
In most other regions, the link between
geology and a wine’s quality is more obscure.
In Bordeaux, very good wines are produced
on sediments of varied geological origin:
Oligocene-heavy clay sediments, Oligocene
limestone and Quaternary alluvium. Some of
the finest wines are produced on Oligocene
Asteries limestone in Saint-Emilion, while
lesser wines are made on the same rock type
in the Entre-Deux-Mers region.
Soil types can be mapped according to
a pedological classification. Some types,
including limestone soils, are known to pro-
duce high-quality wines, while others, like soils
subject to water logging, are not. Yet, across
the world, outstanding wines are grown on a
huge variety of soils. In the Bordeaux area, top
wines are produced on soils as different as

8. the main terroir factors are involved and inter-
act (climate, soil, grapevine).
Gérard Seguin was the first scientist to study
vine water uptake, using a neutron moisture
probe in the soils of the Haut-Médoc. He
demonstrated that a grape’s quality potential was
related to regular but moderate water supply
to the vines. In non-irrigated field conditions
where vines face water deficits, berries are
smaller and total phenols higher. The result is
good grape quality potential for red wines, but
lower yields. Berries ripen faster when the vines
have less water. If there is a severe lack of water,
the aroma potential of white grapes can lessen.
Irrigation can modify vine water uptake,
increasing not only the production of sugar and
skin phenols per vine, but also yield. Yield gen-
erally increases more rapidly than sugar and
skin phenols on a per vine basis, sometimes
resulting in dilution. In dry regions, only deficit
irrigation can produce economically acceptable
yields with high-quality potential grapes.
Irrigation is likely to modify terroir expression.
The ideal water status is highly dependent on
yield. In dry farmed vineyards in dry areas,
excellent red wines can be made from fruit
grown on severely water-stressed vines, as long
as the yield is very low. For higher yields, the
best results in terms of quality are obtained
when the water deficit is mild, as through
deficit irrigation.
Privation is the way to the best terroir
The highest expression of terroir is obtained in
cool-climate viticulture, when the precocious-
ness of the grapevine variety allows the fruit to
ripen at the end of the growing season (the end
of September in the northern hemisphere). For
full ripeness, early-ripening varieties are suited
to cool climates and late-ripening varieties to
warmer climates, so that grape ripening doesn’t
occur during the hottest summer months.
In order to obtain high grape-quality for
red wines, the vine’s vigour and berry size
must be controlled, and its grape skin phenols
increased. In most terroirs known for high-
quality performance, the limiting factor is mild
water deficit, either because the climate is dry
or because the soil water holding capacity is
low – usually because of high pebble content
or shallow soil. Hence, high-quality potential
viticultural soils are either stony or shallow.
In the case of red wines, low nitrogen supply in
the soil can also be a quality factor. For white
wines, water and nitrogen supply to the vines
should be moderate at least, because severe
stress can harm the grape’s aroma potential.
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