After about 20 years vines start to produce smaller crops, and average yields decrease, leading to more concentrated, intense wines.
[2][3][4] In the South Tyrol wine region of northeast Italy, a more than 350-year-old vine of Versoaln planted at Castel Katzenzungen is being used to produce wine with the fruit of the old vine blended with the fruit of younger plantings to produce approximately 500 bottles a year.
In the Barossa Valley of Australia, the world's oldest continually producing commercial vineyard that has been authenticated is believed to be the Shiraz vines at Turkey Flat in Tanunda that were originally planted in 1847.
Similarly, if a producer sells a "regular" and "old vines" bottling, it is more likely to represent a perceptible difference in character, if not necessarily in quality.
In these ways, "old vines" is similar to "reserve," a term that also varies dramatically in its significance and in many countries and regions has no legal definition.