Vinalia

Vinalia

April 23, August 19

There were two ancient Roman festivals that were sacred to Venus and known as the Vinalia. The first, observed on April 23, was called the Vinalia Priora ; the second, on August 19, was the Vinalia Rustica . Both festivals, it seems, were originally sacred to Jupiter. But after the worship of Venus was introduced into Rome in the second century b.c.e., its popularity spread so quickly that the older association with Jupiter gradually faded.
April 23 was probably the day on which the wineskins were first opened, the new wine having been brought into Rome just a few days earlier. Libations from the newly opened skins were made to Jupiter (later Venus, who was a deity of gardens and therefore of vineyards as well). After the libation, the wine was tasted. Winegrowers were warned not to bring the new wine into the city until the Vinalia had been proclaimed on the nones, or the ninth day before the Ides of the month.
There is some confusion about what went on at the August festival. Some believe that this—not April 23—was the day on which the new wine was brought into Rome. Others say that the Vinalia Rustica was a rite designed to protect the vintage that would follow from disease, storms, and other harmful influences.

SOURCES:
FestRom-1981, pp. 106, 177
OxYear-1999, pp. 166, 338
RomFest-1925, p. 85