Santorini: A Chain of Probable Events Part II

Viticulture and the Volcanic Soils of Santorini

Santorini is one of the peaks formed along the South Aegean Volcanic Arc, a string of volcanoes aligned along a 500 km (300 mile) long and 40 km (25 mile) wide semi-circular sweep from just offshore of Athens, south through Santorini and west to the Turkish coast. Nisyros, Milos, Egina and Poros are the other main volcanic islands of this zone, also known as the Hellenic Volcanic Arc.

This is the most seismically active area in the entire Mediterranean and western Eurasia, lying along the most stressed meeting point of the African and Eurasian tectonic plates, also responsible for Italy’s volcanic geography. Just south of Crete, the African plate is subducting under the Aegean Sea plate (a fractured portion of the much larger Eurasian plate), giving rise to the parallel volcanic arc some 140 km (85 miles) to the north of the subduction zone where magma from the melting African plate finds its way back up to the earth’s surface.

The climate of Santorini is extreme. Very little rain falls, and mostly only in the winter months. Winds can be ferocious, and blow for weeks on end. The summer sun is relentless, even if temperatures rarely soar to uncomfortable levels. Humidity ranges from near 100% to very low, dropping precipitously as the sun rises and winds pick up.  Everything that lives and grows on the island has had to adapt to these harsh conditions and yields are punishingly low. Only the hardiest of plants, forgiving and undemanding, can survive. But those that do, the favas, tomatoes, barley, herbs, for example, and of course grapes, have an incomparable taste as a result of a life of hardship: concentrated, intense, suffused with flavor, an archetype of themselves.

Soil is not really the right term for the surface material of Santorini. Being a mere few thousand years old, most of what is visible is un-weathered, coarse-textured pumice, volcanic ash and rock. In many areas layers of ash and rock have fused together into a very compact, hard tuffaceous stone called locally aspa. Although very hard to till and cultivate, aspa, like other forms of tephra, have the useful property of being able to absorb and retain water. In the dry climate of Santorini, this very property is what makes grape growing possible. Scarce rains are held in the ground and released throughout the long dry growing season. But those rare winter gifts from Zeus alone would not be sufficient; the kindness of Poseidon is called upon to supplement them during the summer, in the form of sea mists. Each night humidity from Santorini’s immense caldera creeps up the high cliffs onto the island where it cools and condenses on vine leaves and seeps into the open pores of the absorbent ground. Even in the height of summer, scratch just a few inches below the surface and you’ll find moisture.

Stony soils, scraggly vines

Aside from the useful physical properties of the soil, its chemical properties also influence the wines of Santorini. Although volcanic ash is generally rich in mineral elements, in such a young undeveloped form, it is dramatically poor in organic matter and clay, resulting in low fertility. The lack of organic material is perpetuated by the fact that very little grows in such a hostile environment, meaning that the cycle of plant growth-death and re-absorption of its organic material into the soil does not occur. Nitrogen, phosphorous and potassium – the three big macro nutrients required by all plants including vines, are in short supply, keeping vine vigour down and yields pitifully low. The situation has certainly improved since the 19th century, but even still, grape harvests versus the prices currently paid for Santorini put winegrowing at the margins of economic sustainability.

The shortage of potassium also appears to have another critical effect on wine composition: the very low pH/high acid for which the white wines of Santorini are known. Although potassium is usually very high in basalt-derived volcanic soils, as in the Azores or Lake Balaton in Hungary, it is low in Santorini’s silica-rich pumice and ash soils. Without this acid buffering element, even in the hot and sunny Sub-Tropical Mediterranean climate and with fully ripe grapes approaching 14% alcohol or more, Santorini wines have a pH of barely 3.0, or even below. That’s the sort of level you’d expect in, say, a high acid grape like Riesling in a marginal northern latitude.

Yiannis Paraskevopoulos with an ancient vine, trained in the kouloura style

The constant winds on Santorini are both menace and a savior. Flights and ferries to the island are frequently disrupted by dangerously high winds, especially from late fall through spring. The winds also pose a threat to vines, whipping up sand and shards of pumice and rock that can tear through leaves, buds and grape skins, damaging the plants and reducing yields. Fluctuating yields are in fact the greatest form of vintage variation, with the size of each year’s crop heavily dependent on conditions during the delicate stages of bud burst and flowering. 

Santorinian winegrowers have learned to adapt over the centuries by developing a unique form of training vines called kouloura. Each season, new shoots from the previous year are woven into a circular shape, which, over several years begins to resemble a basket, lying right on the ground. No posts, wires or trellising of any kind are used. Grape bunches grow within the basket, protected from wind-borne projectiles, while a canopy of leaves protects grapes from excessive sun exposure.

Old Vines

After several decades, the yields of these basket-vines drop to un-economical yields, given the tremendous distance nutrients must travel through the coiled canes to reach the grapes. At around 70-80 years old, the vines are cut at the surface, and a new shoot is allowed to grow from the root system and the process begins anew. 

The lack of clay and the abundance of sand– another advantage of Santorini’s young volcanic soils - means that phylloxera has never posed a threat, and the island remains phylloxera free; replanting is unnecessary. It’s known that the renewal has been performed at least four or five times on certain vines, making the root systems of the island’s oldest vines hundreds of years old, even if on the surface the vines appear to be young. The vineyards of Santorini are believed to be the world’s oldest under continuous cultivation for hundreds if not thousands of years.

But winds bring benefits as well. During summer, the cool, refreshing north wind called the Meltemia lowers nighttime temperatures to below the dew point, allowing precious drops of water to condense and be absorbed by vines. Daytime winds have the opposite benefit of stripping atmospheric humidity, which, coupled with heat, would otherwise create an ideal environment for molds, mildews and fungi to flourish. As it stands, most growers farm essentially organically, whether declared or not, needing only an occasional dose of copper to keep vine disease at bay.

Vineyards

Vineyards, southern Santorini

There are some 1200 ha under vine on Santorini, about three-quarters of which are in the south around the villages of Pyrgos, Megalochori and Akrotiri. This is barely a third of the acreage during the island’s 19th century heyday, when grapes blanketed the island and were virtually the only commercial crop. Crops of tourists are Santorini’s economic mainstay today, a far easier and more lucrative harvest than toiling away in unforgiving and ungenerous vineyards. Land prices have soared. But the crisis for the future of Santorini wine seems to have passed. There are signs that tourism and its associated amenities have reached the saturation point, encouraging a new generation to return to old viticultural traditions. New virtual, and bricks and mortar, wineries have emerged, bringing the island’s total to about a dozen and a half. And with the steady increase in international interest and accompanying price increases, the future of Santorini wine appears at least stable.

Grapes and Wine Styles

In the distant past there were as many as 50 varieties grown on Santorini, though now just three white grapes dominated production. Assyrtiko occupies three-quarters of Santorini’s vineyards, selected over centuries for its thick, disease resistance skins, ability to retain high acids even at high alcohol levels, and chart-topping extract. It’s considered one of Greece’s finest white varieties, and has since been planted all over Greece, though no other region yet matches the heights of Santorini Assyrtiko. Very likely the wines that made Santorini’s past fortunes, able to survive long sea voyages, were based largely on this grape. By law, wine labeled as dry PDO Santorini is at least 75% Assyrtiko, though in practice the percentage is higher.

Modern amphorae, Gaia Estate

Athiri and Aidani are the other two main varieties permitted in the PDO Santorini, more occasionally appearing on their own under the PGI Cyclades regional appellation. Athiri’s contribution is to soften and lighten the blunt intensity and weight Assyrtiko, while Aidani is prized for its intense, fruity aromatics, a feature which Assyrtiko lacks. Traditionally these grapes were interplanted, harvested, and vinified together, especially for the production of delectably sweet PDO Vinsanto, the original “Vino di Santorini” as it was known to Venetians traders, and emulated later in Italy under the name vinsanto.

Vinsanto is invariably a blend of these grapes (at least 51% Assyrtiko, by law), harvested and left to dry in the sun for up to two weeks before pressing and fermentation. A minimum of two years ageing in wood casks is required, but the most prized bottlings stay much longer in wood, up to 10 or 20 years. Vinsanto can be bottled as either a single vintage, or as a blend, with a minimum age indication in multiples of four: four years old, eight years old, etc. The finest examples are hyper-concentrated essences of the island, challenging, with dizzying sugar levels countered by forceful acids, notably tannic bitterness and palpable astringency.

Nychteri (nichteri, nykteri) is probably the closest in style to the powerful dry wines of centuries past. It’s made from the same grapes permitted for PDO Santorini, late-harvested (usually one to two weeks after those destined for straight Santorini), and often weighs in at 15%-16% alcohol, occasionally with some sugar left over. By law today it must be aged in wood for at least three months, though historic versions surely spent far longer, up to two or three years, in cask.

A small quantity of mostly dry red and rosé is made from Mavrotragano (literally “black crunchy”), a deeply coloured, tannic, high acid variety considered to be Santorini’s best. Mandilaria is another tart and tannic red grape better known on Crete, while rarer still is Voudomato, a relatively pale, soft red often used to make Santorini’s increasingly scare sweet red blends (under PGI Cyclades).

Recommended Producers:

Argyros; Gaia; Hatzidakis; Sigalas; Vassaltis

Text and Photos by John Szabo, MS