The reason for this is to be sought partly in the unscientific methods of cultivation, and partly, in many districts, in the haphazard methods of vinification employed.
The process of vinification is peculiar in that fermentation takes place in relatively small casks, the result being that there are frequently marked differences in the produce of the same growth and vintage.
The method of vinification is similar to that employed in other parts of Portugal, but the method employed for hastening the maturation of the wine is peculiar and characteristic. This consists in subjecting the wine, in buildings specially designed for this purpose, to a high temperature for a period of some months.
The vines, the methods of viticulture and vinification as regards the red wines of the Graves district, are similar to those of the Medoc. The wines are, if anything, slightly fuller in body and more alcoholic than those of the latter region.