We cooperate with several riding stables, so the horseback rides are not all done in the same place.
That said, especially for beginners, you need flat, “protected” terrain, and vineyards are not very suitable. In addition to this paramount issue, vineyards are privately owned, and the owners do not always like novice riders who might damage the plants and soil. Among other things, the instructor, in a vineyard, could hardly follow you closely.
In any case, the locations chosen are scenically stunning, mostly forested and will allow you to have a magnificent experience in contact with nature.