Grape vines can be grown in a wide variety of soil types and climatic conditions. They are a hardy plant and are usually grown from cuttings. To successfully grow a vine involves the construction of a trellis system, irrigation, soil amelioration (to fix soil problems), planting, training to the trellis, removal of buds and leaves from the trunk, weed control, pruning, pest and disease control, harvesting and a great deal of time, patience and maybe a little luck as well.
Grapes are largely grown on a support structure known as a trellis. The trellis may be as simple as a single post-end assembly with a single wire or it can be quite elaborate with multiple wires.
Vines can be grown on their own roots or grafted to another variety's root system (rootstock). Rootstocks are chosen for their ability to be tolerant or resistant to moisture, drought, disease, pests or any variety of potential problems. Vines are usually hand-planted.
Winter brings on dormancy in the vines and at this stage they can be pruned to improve the shape and make the vine more productive. The fruitfulness of the vine is determined in the previous growing season and the amount of potential bunches is related to the number of buds left after pruning.
The grapevine has the ability to self-regulate and the environmental factors of a vineyard will determine how much fruit is produced and ripened. Vine balance can be calculated with a mathematical equation.
Shortly after budburst in spring groups of flowers are produced and the fruit clusters develop from these. The grape berry is made up of pulp, seeds and skin that has a thin, waxy layer with many millions of native yeast cells.
As the berries grow they are hard and contain mainly grape acids (malic and tartaric acids). As the grapes ripen they start to soften and change colour. This is called veraison. Sugar, flavour and water content starts to increase and acids decline.
At this stage the major components of the grape berry are:
Ripeness and harvest is determined by the winemaker taking into consideration the style of wine to be made. The acid content is not a major concern as this can be added to the wine, usually in the form of tartaric acid. The main determinant is colour, flavour and sugar level. Neutral juice of low colour and sugar will not produce an interesting wine.
Grapes are harvested either by hand or mechanically.
