(Third in a series of opinionated articles about wines and winemaking)
Grape growing is one of those pursuits that alternates between long periods of inactivity and days or weeks of blinding fury. The annual journey begins in the spring, usually April in this area (but actually March for many varieties this year), when the first green leaves begin to appear at “bud break.” This is the first time each year after which the grape grower can only stand by and pray for good weather, since a severe frost in the first few weeks after bud break can devastate the crop (1999 and 2011 were good examples of Mother Nature’s little jokes, when a late May frost took out many of the county’s white grapes as well as much of the tree fruit). This risk also has its reward. Since the young shoots grow by as much as two inches per day they can provide a profound sense of renewal each spring when the vines go from stark, grizzled trunks to a lush field of brilliant green in only a few weeks.
The second risky period is during flowering of the vines, which generally occurs about six to eight weeks after bud break. Excessive heat or significant rain (it seems we get one or the other each year) during this critical time can dramatically decrease the crop yield by decreasing pollination efficiency.
Care and Feeding of the Vines
It’s been said that the best fertilizer for a vineyard is the shadow of the owner. Constant vigilance is required to assess insect or powdery mildew problems, and a sound program of pest management must be in place if the harvest is to be successful. Here again, professional help is not only a good idea, it’s the law. The number of available agents to control pests in the vineyard has declined steadily each year, as we learn more about the health and environmental impact of products we used to rely on. Each agent has its own requirements for application rate, repeat interval, and hazards to workers and the environment. For these reasons, a licensed Pest Control Applicator must direct the use of vineyard chemicals. (You can engage in chemical warfare as most growers do, or if you choose, you can grow grapes organically, but that approach requires both knowledge and substantial effort. A few growers, notably Brian Fitzpatrick in this area, have been quite successful with a totally organic approach to grape growing.)
Actual fertilizer is sometimes required; in this area primarily phosphorus and a few other minerals termed micronutrients. Determining what’s needed and how much is best done by analysis of the leaf stems (called petioles) gathered at bloom time and sent to a lab. Both sampling and interpretation of the results require some training and may best be left to professionals.
The dominant problem during the rainy spring months (and the rainy summer months that often revisit us) is powdery mildew. A regular program of spraying is necessary for its control, and in some cases removal of excess leaves may be necessary to allow spray penetration and moisture dispersal. A bewildering array of insect pests can appear at various times, and their evaluation and eradication requires both training and experience. (In both grape growing and winemaking, extension courses are available from U.C. Davis to provide either general background or in-depth knowledge. You can get a catalog of available courses by calling (800) 752-0881.)
After surviving the summer onslaught of mildew, insects, and weeds, harvest time approaches, usually in late September. (But recent years have seen harvests that began in late August to late October, so don’t plan your vacation in the spring). Early bud break usually corresponds to an early harvest, and we’ll see if that holds true this year. One of the more difficult tasks is to determine when to pick the grapes. Different wineries will want slightly higher or lower sugar levels; normally grapes are picked when the sugar content of the juice is about 23 to 24 percent, but at our elevation, 25 or 26 more often corresponds to actual biological ripeness. Wineries can do precise laboratory analysis to determine sugar content, or a hand-held refractometer (about $250) can give you a good spot check in the field. Experienced grape farmers will tell you, however, that no test will substitute for taste–when the grapes taste ripe, it’s time to pick.
Picking is the most intense of any activity in the vineyard. In hot weather, grapes can go from just right to overripe in only a few days, and the grapes must be picked and transported to the winery in as short a time as possible. Picking crews are always difficult to schedule, since all your neighbors’ grapes are ripe at the same time as yours, but somehow it always gets done. Once the last berry is picked, you can finally lean back, relax–and begin to worry about next year’s crop.
The final event of the vine’s year is pruning, or removal of the excess woody growth from the past year. There is both a science and an art to pruning, and the needs vary with the grape variety, style of trellising, the age of the vineyard, the amount of water available, and at least a hundred other factors. If you want to do this yourself, you would be well advised to serve an apprenticeship in a nearby vineyard, since the success of next year’s crop (and beyond) can depend on those split-second decisions of which spurs and how many buds to leave for the future. It should be done when the vines are dormant in the winter, but can in some cases be left until the following spring when it can help to delay bud break and lessen the chance of frost damage. Besides, there is no prettier sight on earth than a vineyard with all the arching canes left on the vines, covered by the soft white blanket of a gentle winter snowfall.
John L. Smith, Oakstone Winery