Grape vines were around long before human beings domesticated them. Today, we bend them to our will with trellis systems, pruning, and propagation through cuttings. But their life cycle remains unchanged.
Grape vines are a woodland, tendril climbing, survivor species. In the wild, seeds are principally spread by birds who eat berries, then excrete seeds while perched in trees.
Seeds germinate, vine attaches to a tree. Above ground the vine begins an upward dash toward sunlight—positive phototropism. Below ground, roots plunge as deep as 20 feet.
Dormant during winter, the first sign of life is “bud break” in early spring. Emergence of new shoots can be perilous when there is late frost. In most cases, however, leaf tips become visible shoots, grow, all goes well.
Tiny flowers appear in one or two months. In dry climates, flowering can be as short as a day or two. In cool, wet conditions it can last a month. After pollination—self pollination in most wine vine circumstances—flowers fall away and newly-formed berries grow rapidly.
The berries are tiny, light green, and taste terrible so birds and others will not eat them. They are bitter, acidic, and have a pepper taste. Some of the pepper from this stage can remain and become a taste in finished wine—in syrah and zinfandel, for example.
Once berries are well-formed, a miracle takes place. Veraison—change of color. Red grapes take on their red or reddish-black color, white grapes remain green but become more translucent. Now the vine focuses its energy into making grapes bigger and sweet. Berries develop glucose and fructose sugars, polyphenols that make varieties distinctive, and begin losing acidity.
A moment of truth presents. Vine growers must stage grape picking when sugar and acidity are in balance. That window can be as short as a single day. Furthermore, not all grapes on a vine balance at the same time. Pinot noir, sangiovese, malbec, and zinfandel are famous for uneven ripening, which is why they are considered among hardest to grow.
Picking at peak is when skills of wine farmers and grape harvesters become critical. Birds, deer, and other wildlife also know grapes are ready to eat, so netting may be used to deter grape-gulping animals. When it all works, ideal berries arrive at the winery. That is when new skills are needed and a new saga begins.
Last round: Best way to protect yourself from sun damaging your skin in summer: drink wine while sitting in the shade.