This is not as easy to answer as you might imagine. The reason is subjectivity. ‘When will this be ready to drink?’ is an impossible question to answer unless you know something about the taste of the person who asked it. Your bottle of mature Bulgarian Cabernet might be my bottle of tired out plonk. The same is true of national preferences: the French regard the British love of older Champagnes as verging on the perverse, while we find some of the bubbly they drink under-ripe.
Other, less subjective factors come into play too, such as the original quality of the wine, the vintage in which it was produced (lighter years mature more rapidly than powerful ones), the temperature at which it was stored (wines develop more slowly in cool conditions) and the size of the bottle (half bottles develop faster than bottles and magnums because the ratio of oxygen to liquid is higher in the wine).
For all that, some wines are better suited to cellaring than others. Reds with plenty of tannin, such as Barolo, red Bordeaux and Port, are obvious candidates, as are top Rhônes (Hermitage, Cornas, Côte Rôtie and Châteauneuf-du-Pape), Tuscan wines such as Brunello di Montalcino, Chianti Classico and the so-called Supertuscans, the best Spanish reds (from Rioja, Ribera del Duero, Priorat and Toro), really good red Burgundy, Australian Shiraz, Napa Valley Cabernet Sauvignon and a handful of South American and South African reds.
Most of these reds have high concentrations of tannins, phenols and colouring matter (known as anthocyanins), which help to keep the wine fresh and stable in its youth. As the liquid ages, so the colour gets paler and the tannins soften (a process known as polymerisation). The tannins fall out of the wine and, by doing so, deprive it of its first defence against gentle oxidation. Over time, the oxygen and the wine interact. As they do, the character of the fruit changes, going from what wine buffs call primary to secondary to tertiary. The mellow aromas and flavours of a mature wine are potentially much more complex than those of a young one. That’s why we wait for great wines to develop.
How long to wait before opening a bottle is partly down to personal taste, but there are what are known as ‘optimum drinking windows’ for most wine styles. Leave it too long and the wine will become brown and maderised; drink it too early and it will seem gawky and unfinished. As the American wine writer, Benjamin Wallace, puts it in his book, ‘The Billionaire’s Vinegar’: ‘Paradoxically, wine is improving even as it is being destroyed; time will kill a wine, but is also necessary to make it great.’ White wines that age well are rarer, but those that are fortified, have high levels of sweetness or high levels of acidity can develop well in bottle. The most ageworthy grape varieties are Chardonnay (especially from top sites in the Burgundian appellations of Chablis, Meursault and Chassagne- and Puligny-Montrachet), Riesling (mainly from Germany, but also from Australia, Alsace and Austria), Chenin Blanc (particularly from the Loire Valley) and Semillon (from Australia, but also as the main grape in Sauternes). I’d also include the fortified wines of Sherry and Madeira, both of which are made from white varieties and can age for a century or more, and Champagne (generally made from one white grape, Chardonnay and two red, Pinot Noir and Pinot Meunier). Some critics argue that only great wines evolve and develop in the bottle. I wouldn’t be that proscriptive – can’t an Albariño, a Sancerre or a Beaujolais be great? – but more often than not this is true. Great wines are wines that reveal themselves over time.