Planting and Grafting
Due to the unforgiving nature of the Douro soils, thorough preparation of the intended site is essential if planting is to be successful. Initially the type of vineyard layout must be decided, based largely on gradient (for details, see the next article about Vineyard Layout). Then it is conditioned using a process called surriba, i.e turning over the top 1.20 metres of the soil across the entire area. Using a bulldozer, a deep ditch is dug and then filled with the earth immediately adjoining, therefore effectively creating another ditch. By working along the ground constantly refilling the ditches, this time-consuming process ensures that the roots of the young vine do not have to penetrate virgin soil. For vertical plantings, the bulldozers always start at the bottom of the slope so that to fill in the ditches they are working downhill. If patamares are being made, work starts at the top of the hill so that any large boulders can be pushed down the slope and buried in the terrace below.
Since phylloxera decimated viticulture in the Douro towards the end of the 19th Century, all vines have been planted on phylloxera-resistant (or American-derived) compatible rootstocks. These can also bring other advantages (such as drought resistance, increased yields or improved mineral uptake) to the grafted scion. Planting a new vineyard therefore requires careful selection of an appropriate rootstock, taking into account such factors as soil type and pH, nutrient status, climate, grapevine variety, likely disease status of the parcel (with particular reference to nematodes) and so on.
The next decision is whether to plant the rootstock first, and then after a year to graft on the scion of the required variety in the field, or to plant bench-grafted rootlings, already consisting of the rootstock and scion combination. The latter have the advantage that the vineyard theoretically comes into production a year earlier, although this method was initially treated with suspicion due to a higher rate of failures. Recent bench grafts, with longer stocks, have eliminated this problem in all but the harshest years. Some degree of watering by hand is likely to be required whatever the chosen method of planting.
Being essentially creepers, grapevines require some sort of physical support, known as a trellis. This consists of a line of posts, placed roughly every five metres, and joined by a series of wires. The most commonly used vine spacing in recent plantations in the Douro is 1.10 metres between the vines and 2.00 metres between the rows. Older vineyards, vinha velha, have narrower spacing in both dimensions and thus cannot be mechanised as the rows are too close to allow the passage of agricultural machinery. Usually the trellis is installed just after planting. Traditionally the trellising posts were split from the very hard blue schist prevalent in the eastern reaches of the Douro, around Foz Côa, but nowadays wooden or metal posts are normally preferred as they are more resilient. They also have the advantage that they can be hammered into the soil whereas the stone posts have to be buried. The first wire, onto which the vine will be trained in due course to form the cordon, is usually 60 cm above the ground. Above it, one metre off the ground, is a pair of double foliage wires, and the same again at 1.40 metres.