Who, and what, is old? When does a child become an adult? What does an adult have, what does she aspire to, what can she communicate that a child has not, does not, cannot? We know adolescents with the wisdom of elders, and leaders of nations with the maturity of kindergartners. All depends on upbringing and context. As with people so with vines, the cardiovascular system of wine.

Wine folks speak frequently about grapes, soil, climate. It’s less often that one hears about vines, except when a label notes that the wine in a particular bottle came from “old vines.” For a long time now I’ve been trying to figure out what this means. No one seems to know.

Or at least, no one seems to agree. In even the world’s most regulated, nit-picky wine regions, with rules about grape varietals, alcohol levels and aging time, vintners seem to have carte blanche to call a wine “old vines” (or “vieilles vignes” in France, “vecchie viti” in Italy, “alte reben” in Germany and Austria, and so on), without mentioning how old. Vintners who farm vines that can comfortably be called “old” tout them as such; vintners with younger vines rarely boast of them, though some explicitly dismiss the assumption that older is better.

Anyway, we’re in a gray area, and ought to refer to “average vine age,” since most vineyards contain vines that were not all “born” at the same time. Some vines get sick, some die. Sometimes a vintner will increase vine density in a given vineyard, adding vines and rootstock to a plot of land that has comfortably housed other vines for decades. Most wines blend grapes from vines of differing ages.

It’s probably safe to say that vines younger than 30 cannot be called old. Beyond that, the terminology gets chaotic. In Australia’s Barossa Valley, for instance, shiraz vines older than 35 are classified as old, but then there are survivor vines (75 years old and more) and even centurion vines (over 100). Genuinely old vines are rampant in Spain, and so anyone there who says “viejo” should be talking about 70 or more. In Campania, Italy, there are vines older than 150; are the 75-year-olds old?