Growing Grapes
It's easy to forget when looking at expensively packaged fine wines in wooden cases or undoing the screwcap on a chilled bottle of Sauvignon Blanc that wine is an agricultural product. Wine is fermented grape juice - pure and simple. Just as top chefs place great importance on the quality of their ingredients, ask any winemaker how to make great wine and they'll tell you that most of the work is done in the vineyard.
Terroir
Different varieties of grapes have different flavour characteristics. In many parts of the world this is considered the most important factor, and so wines are labelled according to their grape variety, such as Cabernet Sauvignon or Chardonnay.
However, there are other things that affect the flavour of grapes and the wines made from them. Hot, sunny climates produce riper grapes with more sugar which generally make richer and more full-bodied wines. Other factors often considered include the type of soil the vine stands in, the vineyard's aspect to the sun, and the practices followed in the vineyard.
The French have a word that sums all this up, terroir. Most French wines (and many from elsewhere in Europe) are labelled according to where they come from rather than the grape variety used to make them. In regions such as Burgundy and Bordeaux they go even further, with vineyards classified into differing "quality" levels according to their terroir.
The Grapevine
The grapevine is a climbing plant that is unable to support itself, which is why almost all vines are planted using some form of trellising. The neat, orderly rows of vines that form part of such famous landscapes as Chianti in Tuscany and the Loire Valley are a result. The exception to this is "bush" vines, which are left free-standing but very low. These are most commonly in warm regions such as Châteauneuf-du-Pape and Rioja, and especially for the Grenache (or Garnacha) grape variety.
The annual cycle of grape growing starts in the winter, when the vines spend the cold months lying dormant. Vine growers (vignerons in French) are anything but dormant however, since there is important pruning to be done. There are many baffling variations of pruning and training techniques are often governed by local tradition and even by law.
In the spring the vine bursts into action, with new, spindly shoots beginning to form as the days warm up and lengthen. At this time frost is a big risk, since it can kill these young shoots and so decimate a crop, such as in Bordeaux in 1991.
Flowering occurs in early summer. A vine's flowers are not very pretty to the eye and look like miniature cauliflowers. Fortunately, they do not need to attract insects either, since fertilisation of the flowers is by wind pollination, although this does mean that poor weather at flowering time can again damage a harvest.
During the summer the vine continues to grow: leaves develop, and berries (which will eventually become grapes) form. The crop yield, which many people regard as key to the quality of the finished wine, becomes important, as the more fruit the vine produces the lower the level of flavour compounds in each grape. For this reason, a "green harvest" may be carried out to remove excess fruit.
As grapes ripen their acidity levels drop and sugar levels increase. A well-known generalisation is that harvest will take place 100 days after flowering although this varies by grape variety and climate - the warmer the weather the faster grapes develop. Quality-conscious vignerons try to pick at optimum "physiological ripeness", when the flavour components of grape juice peak and so give the most flavour the resulting wine.
Grapes can be harvested by hand or machine. Machines are faster and more cost-effective for large vineyards, but are not suited to difficult terrain such as in the Mosel Valley in Germany or Douro Valley in Portugal. Also, machines are not selective, so for many top wines hand-picking is preferred since poor fruit can be rejected.