Riesling around the world have two Old World prototypes to copy (or, alternatively, to rebel against). There is the flowery Germanic style, or the weightier, winier example from Alsace. So far only Australia has succeeded in establishing a home-grown style of equal stature, and its wines are more like those of Alsace than those of Germany. The Germanic style appears in watered-down versions elsewhere – showing, perhaps, how difficult it is to get right.

Riesling around the world

Rieslings from Germany depend on acidity as taut as piano wire, yet they can be as seemingly delicate as a butterfly. The fruit can be intense yet ethereal, the residual sugar (if there is any) must be integrated and honeyed, and if the alcohol is low, the extract must be sufficient to give the wine balance.

That, admittedly, is not the pattern all over Germany. In the South – in the Pfalz and Baden – the wines are drier and weightier, with more substance. But they should still have that taut, knife-edge balance. The further north you go, the more apparently ethereal the wines become. Wines from the Rheingau and Nahe have more weight than those from the Ahr or the Mosel; and within this latter region, wines from the Saar and, especially, the Ruwer, seem ever more delicate.

The paradox of German Rieslings is that, like a consumptive operatic heroine, they appear to be ready to collapse in the first scene, yet are in fact quite capable of lasting the full three Acts and singing half a dozen physically demanding arias into the bargain. These frail-seeming Rieslings are fit, lithe athletes – and potentially some of the longest-lived wines in the world.

To fulfil their potential as the wine world’s marathon winners, Rieslings need concentration. In the Rheingau the average yield is around 100–140hl/ha on the flatter land nearer the river, and perhaps 50–65hl/ha on the less fertile slopes. On a good soil, with good vineyard management, it is probably possible to raise the yield to 85–90hl/ha without quality problems – but that is in an ideal year, with sufficient sun and rain.

The Rheingau doesn’t always get enough sun. In the Mosel yields are generally higher, in spite of the exceptionally poor soil: 180hl/ha is not uncommon, and yields of this magnitude do not produce concentrated Riesling. Quality-conscious growers do not allow their vines to yield as generously as this: most quote an average yield of 50–70hl/ha, with the figure going down to 35hl/ha for very old vines. (The Rheingau equivalent might be an average yield of 45–50hl/ha from a top grower.)

More strictly selected wines like Auslese (made from selected clusters), Beerenauslese (from selected berries) and Trockenbeerenauslese (from selected berries that have been shrivelled by botrytis) are lower again.

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Why should yields in the Mosel, where the soil in the best vineyards consists of nothing but flat shards of slate balanced on a steep hill, be so much higher? One reason is that Mosel Riesling sells for less in Germany than its counterpart from, say, the Pfalz, so growers are not prepared to sacrifice any quantity. Yet the Mosel demands greater effort: 1ha (2.5 acres) of vineyard in the Mosel requires 1200 hours of work per year.

In the Pfalz, 800 hours is average. In the Saar and Ruwer, where the climate is even less promising than that of the Mosel, yields are lower. The regions are close together, but even half a degree centigrade can be the difference between losing part of your crop to frost and escaping, or between reaching, or failing to reach, an acceptable ripeness in your grapes.