The wine-making process lasts all year, and culminates in most regions in September and October as the grapes ripen. To the wine maker there are four seasons: winter, spring, summer and crush.
Crush is a steady parade of grapes. In California, pinot noir and chardonnay are among the first to come in to be crushed, as early as August, and cabernet sauvignon and zinfandel might not be ready until November.
The process of making wines actually begins, however, in the dead of winter. By winter the vines have dropped their leaves and gone dormant, awaiting the first warm breath of spring. The pruning crews move into the rows of tangled branches, carefully cutting out the old growth that carried last year's fruit and will never again be fruitful. Young shoots that will carry next year's crop are selected and trimmed to the length at which they will best be able to support the full weight of autumn's bloated grapes.
Only a few buds can be left, lest the reproductive instincts of the vine commit it to more grapes than the photosynthesizing leaves can produce sugar for. Ripeness in the grape is directly related to the ratio of leaves to fruit, and an experienced pruner knows just how much fruit the vine can support.
In some vineyards the young fruit-bearing wood has to be tied to a clothesline-like trellis to help support all the weight. Because the vine's trunk and branches are the pipelines of food and water for the leaves and fruit, and for the energy the vine stores through the dormant season, the ties must be made loosely lest the growing branches strangle.
The pruning crews also remove diseased and damaged parts of the vine. In cold climates like Germany and New York state, there is often winter kill and splitting where the vine has been exposed to the ravages of a harsh winter.
As spring approaches, the relatively warm water of melting snow and spring rain awakens the slumbering root system, which begins to pump sap through the varicose-like veins of the vines. Far more sap is pumped than can be used, and the ends of the cut canes weep with the overflow.
The sap causes the buds to swell, pushing a cottony wisp, testing the air, through the skimpily clad, crusty bud shell. Spun and sometimes pink like cotton candy, the buds balloon in the seductive spring breezes.
False springs that promise but never deliver are a death trap for the helpless buds and the tender leaves. Once they have appeared, a few hours of hard freeze can spell disaster, nipping in the bud the crop before it has hardly begun.
To avoid an untimely end to the vintage, owners resort to a variety of practices. They light smudge pots of oil, burn old tires, blow warm air around with huge aircraft propellers, spray water on the young buds, and pray a lot. Spraying water seems an unlikely method for preventing frost damage, but the water coats the vulnerable new growth with an icy armor that remains at freezing temperature, protecting the delicate growth with an icy armor that remains at freezing temperature, protecting the delicate greenery from temperatures several degrees below freezing.
With continued warmth, the balloon-shaped buds begin to differentiate and the leaves begin to form, opening like cupped hands to reveal another pair of hand-like leaflets within.
Vines are efficient solar energy producers, and they grow rapidly and rotate toward the sun. By the solstice, new shoots stretch a yard or more, and tender tendrils reach for something to grasp to secure the apparatus in the wind. With the lengthening days, the flower buds form on the new green shoots.
The configuration of the bouquet of grape flowers foreshadows the future shape of the grape bunches. Clusters of slender pistils, sticky with pollen, drop their seed to the waiting clusters of stamen. The delicate flower is sensitive to any environmental trauma, and frost or precipitation are perilous to the process. If rain washes away enough pollen, only a few flowers will fertilize themselves, and the bunch will form skimpily, with fewer berries; the resulting crop will be correspondingly skimpy. Only after the flowers have set their fruit will the anxious grower begin to feel confident.
As the dog days of summer arrive, the vine provides its developing offspring with a lush green canopy for protection from sunburn, hail and birds. But what will protect the leaves from numerous diseases, mildews and insects?
Growers must return to the vineyards and spray regularly to combat such dread enemies as powdery mildew, black rot and botrytis cinerea. The latter is the same fungus that is called the "noble rot" when it attacks ripe grapes and concentrates their sugars by dehydrating them. The remaining juice turns into thick nectar from which some of the world's finest sweet wines are made. But early in the season the "noble rot" is not as welcome a guest as during the harvest.
Through June, July and August, the bunches fatten and fill with juice. Sun, sun and more sun are necessary to stock the bulbous sugar warehouses, and late in the summer they begin to ripen. The changing of color of the grapes begins six or seven weeks before the picking begins. Green grapes become translucent, and purple grapes start to develop their color, slowly changing from hard green pellets to soft purple bubbles of sugar water.
In the better vineyards the grower returns several times each summer to plow under weeds. Quality growers also will strip the vine of some bunches when it appears there are too many for the vine to ripen properly.
Although the weather during the summer is important, the last few weeks between color change and harvest are the most crucial.
Dry air is essential. High humidity or rain provides the perfect environment for fungal growth, especially within the tightening bunch of expanding berries. Rains can also cause some berries to split open, spilling out their sweet juice and attracting flies, bees and birds, along with the attendant contaminations. A large flock of birds can decimate a vineyard in a few hours.
Against this winged menace, viticulturists have devised several methods of protection: Some broadcast imitations of birds' distress calls across the vineyards, others roll netting over the rows of vines, others honk automatic automobile horns, some spray a chemical that makes the birds' stomachs upset and still others resort to standing guard with shotguns.
Finally, when sugar levels reach 18 to 22 percent and the acid is at a level the wine makers consider properly balanced with sugar, the grapes are ready to pick. (Sugar is converted to alcohol during fermentation.) If conditions are right, some adventurous growers will leave grapes on the vine long enough to develop sufficient sugar to make a wine with residual sweetness when fermentation stops.
Normally this option is not available, and the grower must be content to pick the fruit one step ahead of the fall frosts. In warm climates like California where the grapes almost always develop adequate sugar, acidity is the crucial factor, and grapes are picked when sugar and acid are in balance. In cooler climates like New York state, acid is not a problem, so grapes are picked as sweet as possible.
Picking is still done by hand in most countries, but where the ground is level, more wineries are moving to mechanical harvesters that shake the grapes off the stems. They are gathered in large gondolas or small boxes and brought to the winery as quickly as possible, lest the grapes crush each other under their own weight and the juice oxidizes before it can be processed.
At the winery the grapes are crushed with rollers that crack the skin, allowing juice to flow. An enzyme is usually added to facilitate the dejuicing, and a preservative, sulphur dioxide, is added to kill wild yeasts and bacteria. White wines are usually pressed soon after crushing in order to separate the juice from the bitter seeds and acidic skins. At this stage some wineries use a centrifuge to remove some dissolved solids.
Crushed red grapes are usually left to steep for a while before the skins are removed in order to leech color and flavor components from the skins and the subcutaneous layer just below.
A special yeast mixture is added to the juice, and the fermentation begins as the yeast eats the sugars and produces heat, carbon dioxide, more yeasts and, of course, alcohol. The fermenting juice fills the winery with a heady, yeasty perfume.
After fermentation is complete (when all the sugar has been turned to alcohol in the case of dry wines or when the wine maker chooses to stop the fermentation by filtering out the yeasts in the case of sweet wines), sugar, fruit acid, water and clarifying agents can be added according to local law, custom or necessity.
The wine must then be removed from the sediment and dead yeasts before they cause undesirable flavors. Winemakers can either filter the juice, centrifuge it, treat it with settling agents or refrigerate it to precipitate acid crystals from which ordinary kitchen cream of tartar can be made.
After aging in 50-gallon redwood vats, 55,000-gallon stainless steel tanks or various other containers, the wine is tasted by the wine maker, who blends wines to provide better balance and to minimize deficiencies. When the wine is deemed fit, it is pumped to the bottling line where it is squirted into the glass container, capped or corked, labeled and boxed. It may then be kept at the winery for further bottle aging, but is usually rushed to the market where an ever growing following purchases this "grape juice" and enjoys it as something much, much more.