Taken from Johnstons Private Life of the Romans.
The making of the wine took place usually in September; the season varied with the soil and the climate. It was anticipated by a festival, the vīnālia rūstica, celebrated on the nineteenth of August. Precisely what the festival meant the Romans themselves did not fully understand, perhaps, but it was probably intended to secure a favorable season for the gathering of the grapes. The general process of making the wine differed little from that familiar to us in Bible stories and still practiced in modern times. After the grapes were gathered, they were first trodden with the bare feet and then pressed in the prēlum or torcular. The juice as it came from the press was called mustum (vīnum), "new (wine)," and was often drunk unfermented, as sweet cider is now. It could be kept sweet from vintage to vintage by being sealed in a jar smeared within and without with pitch and immersed for several weeks in cold water or buried in moist sand. It was also preserved by evaporation over a fire; when it was reduced one-half in this way, it became a grape jelly (dēfrutum) and was used as a basis for various beverages and for other purposes.
Fermented wine (vīnum) was made by collecting the mustum in huge vat-like jars. One of these was large enough to hide a man and held a hundred gallons or more. These were covered with pitch within and without and partially buried in the ground in cellars or vaults (vīnāriae cellae), in which they remained permanently. After they were nearly filled with the mustum, they were left uncovered during the process of fermentation, which lasted under ordinary circumstances about nine days. They were often tightly sealed, and opened only when the wine required attention or was to be removed. The cheaper wines were used directly from the dōlia; but the choicer kinds were drawn off after a year into smaller jars (amphorae), clarified and even "doctored" in various ways, and finally stored in depositories often entirely distinct from the cellars. A favorite place was a room in the upper story of the house, where the wine was aged by the heat rising from a furnace or even by the smoke from the hearth. The amphorae were often marked with the name of the wine, and the names of the consuls for the year in which they were filled.