Assyrtiko

Assyrtiko is Greece's great white grape, and its home on Santorini is one of the most extreme vineyard environments in the world. The island is a volcanic caldera with almost no rainfall, no clay in the soil, and a relentless summer wind, and the vines survive on moisture condensing out of the night air onto volcanic ash.

The traditional response to the wind is the kouloura: the vine is woven into a low basket on the ground, with the fruit hanging inside the coil, protected from the gales and the sun. It is labour-intensive, impossible to mechanise, and the vines are extremely old — because Santorini's soil has no clay, phylloxera cannot survive there, and many root systems are centuries old, periodically cut back and regrown.

The wine is unlike any other white. Assyrtiko keeps ferociously high acidity even at fifteen per cent alcohol, which is a rare combination, and produces something powerful, dry and saline, with lemon, grapefruit, green apple and a smoky, flinty mineral character that seems to come straight out of the volcanic ground.

It ages remarkably well, developing a waxy, nutty depth over a decade, and some producers age it oxidatively in old barrels for a wine called Nykteri. Vinsanto — unrelated to Tuscan Vin Santo despite the name — is the island's sun-dried sweet wine, made from the same grape and capable of lasting for generations.

It is now planted across mainland Greece, where it gives a fresher, less intense but still distinctive wine.

The kouloura basket-training is being quietly abandoned in places, which is worth knowing. It is extraordinarily labour-intensive, cannot be mechanised, and Santorini's tourism economy pays far better than viticulture, so vineyard area has fallen sharply and grape prices have risen to among the highest in Europe.

The island's vines are ungrafted and extremely old. Because the volcanic ash contains no clay, phylloxera cannot move through it, and the traditional practice is to cut the vine back to the base every few decades and let it regrow from the same root system — meaning some root stocks are centuries old even though the visible plant is not.

Assyrtiko's unusual ability to hold acidity at high alcohol has made it a subject of real interest as other regions warm, and plantings have appeared in Australia, California and elsewhere. Whether the grape carries its character away from volcanic soil is still an open question.