In terms of vineyard layout, planting in the Douro poses a multitude of problems essentially associated with the very steep and rocky terrain which is more suited to growing goats than grapes. Solving these issues is an ongoing process but its evolution has, so far, followed four distinct phases. They are shaped largely by the availability of money, labour and technology. In chronological order, the main developments are explained below.
Originally the vines were planted at high density on thin, flat and often irregular terraces (patamares) supported by dry stone walls. These walls were often very thick to use up the vast amounts of rock that had to be dug out of the earth to form the flat surfaces, and therefore enormously labour-intensive. The workforce was largely Spanish, made up from Galicians who had come across the border in search of work.
Usually between one and three rows of vines were grown on each terrace, and sometimes small holes were left in the walls from which vines would grow outwards. This minimised wasted space and provided some limited shade for the vineyard workers. Planting density was around 6500 vines / ha. This type of planting is restricted to the period before phylloxera ravaged the vineyards of Europe at the end of the 19th Century. When the Douro was replanted with vines on rootstocks post-phylloxera, the cost of labour made construction of the walls prohibitive and therefore the traditional patamares hardly exist today. In some places they can still be seen, but are often planted with olive trees now.
One way in which vines could be replanted more cheaply was to build fewer stone walls (muros) in the vineyard. The post-phylloxera plantings are therefore characterised by much broader walled terraces which, though sloping, are obviously not as steep as the hillside itself. The rows of vines are planted across the slope, and usually between ten and twenty rows of vines are planted per socalco, depending on the gradient. Planting density is similar to the old patamares, but they have the added advantage of easier access for working with mules. Nowadays these socalcos are also known as vinha velha, or old vines, in contrast with the very different vineyards planted as a result of the recent advent of mechanisation. Yields from vinha velha are very low (around 1 – 1.5 kg / vine) because they are all over 30 years old, but the concentration is excellent.
From around 1965, increasing use of bulldozers allowed a return to contour planting and saw the birth of the second generation of patamares. These do not have vertical stone walls but very steeply inclined banks (or taludes) instead, which is far cheaper. As the earth cut from the face of the slope is used to make the banks they are essentially unstable, and prone to collapse in periods of high rainfall. Although mechanised, the need to keep the taludes free from weeds is expensive and time-consuming. Vines are usually spaced at 1.10 by 2.00 metres, but due to the ground lost to the banks, planting density is around 3500 – 3800 vines / ha. Most patamares are about 3.50 metres wide, and planted with two rows on vines. Some quintas use so-called patamares estreitos, or narrow patamares, planted with only a single row on the outside of the terrace. Planting density may or may not be improved, but maintenance of the taludes is considerably reduced.
Note that when one speaks of ‘mechanisation’ in the Douro that does not mean with reference to pruning or picking, which are both done by hand. It means that a small (1.20 metre wide) tracked tractor can be driven between the rows which may be used for cultivation, spraying, pre-pruning and trimming. Also consider that, where practical, wheeled tractors have the advantage of working considerably faster than their tracked counterparts.
Vinha ao Alto
Vinha ao alto, or vertical planting of the rows up the face of the slopes, is the most recent stage in vineyard development, coming into fashion in the 1970s. It is generally considered that 30º is the maximum gradient for planting with vinha ao alto because of the capabilities of the tractors and in terms of minimising soil erosion. Vine spacing is again around 1.10 x 2.00 metres, giving a density of 4500 – 5000 vines / ha. Like the new patamares, vinha ao alto is always planted in blocks of a single variety while the two more traditional methods are a more or less random mixture of varieties. This was done deliberately to even out production across the years as a form of insurance against the erratic yields of some of the grape varieties which might otherwise cause cash-flow problems for the producers.