The grapevine is a word for gossip. Anything heard on the grapevine was learned by word of mouth. In the Civil War, a grapevine telegraph was a gadget used for communicating. From there, people started talking about "the grapevine" as a source of information, especially gossip.

This phrase "heard it on the grapevine" or "heard it though the grapevine" is a nice way of saying that one heard the information by means of gossip and rumor. Example of use: "I heard on the grapevine that my sister-in-law got the promotion, but I really don't know much about it."

So, how long do grape vines produce fruit? A mature vine will produce fruit for decades! However, typically after 30 years, a grape vine's production decreases—though it's still capable of bearing fruit for much longer. Well-tended vines can live for 50, 80, or even 100 years.

Vines only actually grow for about eight months of the year. In the Autumn they drop their leaves and remain dormant throughout the winter, conserving their energy for the next crop. Even a vine needs to rest at some point to keep producing its best work.