Madeira's fortified wines keep practically for ever - they have been known to survive for more than two centuries.
Out in the Atlantic, on the same latitude as Casablanca, the island enjoys mild temperatures throughout the year, but the climate is also strongly influenced by the ocean. It is extremely mountainous, with deep valleys and steep slopes where the vines grow on little terraces in fertile, acid, volcanic soils that are very rich in organic matter.
Vines are mostly trained on traditional pergolas, the bunches hanging below, shaded from the sun by exuberant foliage. Yields are high. The resulting grapes have high acidity – a distinguishing feature that they pass on to all Madeira wines.
A small clutch of historic Madeira grapes are known as the ‘noble’ varieties: Sercial, Verdelho, Boal, Malvasia (sometimes called Malmsey) and the rarer Terrantez. All are white, and the first four are traditionally vinified to give different degrees of sweetness in the finished wine: respectively dry, medium-dry, medium-sweet and sweet.
Terrantez makes fine, dry wines with very marked acidity. However, 80 per cent of the island’s vineyards are planted with another variety, Tinta Negra, which is made into fortified wines of all four traditional sweetnesses. Some table wines are also made on the islands.