Portugal, as a wine-making region, has an incredible diversity of native grapes that is virtually without equal. Estimates of the number
of grapes grown in the region range from at least 240 different kinds of vitis vinifera, and upward. Representative of that diversity is the Douro region, split into three major parts that grow up to 130 different grape varieties. Three things to help understand the Douro region of Portugal.
How the Douro varies, by region. The three regions, all of which are shielded by the mountain range, Baixo Corgo, Cima Corgo and Douro Superior. Although all three are considered the Douro, the regions have extremely different characteristics, one of which is very different average rainfall. Baixo Corgo, the closest to the Portuguese Coast, gets
around 800 mm of rain, or nearly 31.5 inches, on average. Cima Corgo gets about 500 mm, or just under 20 inches, while Douro Superior is an arid region that gets 300 mm per year, or a mere 11 inches of rain. This is an incredible variation, which calls for very different viticultural practices. Vineyards in Baixo Corgo battle fungi and powdery mildew in ways similar to other, fairly wet regions, whereas a few miles inland, these are the least of their problems.
The north vs. the south. Vineyard managers in the Cima and Baixo Corgo regions point out the oddity of “upper“ and “lower” regions of the Corgo river having nothing to do with the use of the Corgo River as a boundary for those parts. Instead, they point out that the north and south facing slopes along the Douro are what create the differences in the vineyards. South-facing vineyards get a lot of sun all year round, and the schist rock reflects more heat during the summer waves of heat. Right around solstice, in June, is when the Queima do Sao Joao (Saint John’s Burn) often hits, either burning grapes, or burning leaf stems so severely, that nutrition can no longer get to the leaf itself. As you look at the north-facing side of the Douro, the tendency is to have an almost lunar-scape of browns, when the vines are in dormancy. The steep north-facing slopes may be cooler in the summer, but they get very little sun in the winter – sometimes only 3 to 5 hours a day, depending on the aspect and orientation of the slope.
Terraces and the interspersing of varieties, historically, for Port wine. The Douro is an interesting region, also, because in essence, there is a wine region within a wine region – i.e. the area from which port wines come, within the greater wine region of the Douro. Historically, this meant planting many varietals within the
same vineyards, because that was what was required for port wines. As matter of quality and quantity control, however, a limited amount of grapes could be used for port, which is a problem for growers. What do you do with the rest of the grapes and their juice?
In some cases, the response has been to make
high quality wines, while embracing all of the varietals that go into a bottle. Some modern vineyards, which are planted in blocks, will have several of the more prominent Portuguese varietals, such as Touriga Nacional, Touriga Franca, Tinta Roriz, Tinta Barroca, Tinta Cão. Other varietals, such as Tinta Francisca and Tinta Amarela (or Trincadeira) are grapes that are coming back into favor, after having waned in popularity, some even now being bottled as a single varietal.