The weather has been so screwy it’s a wonder that migrating birds know when to return or when perennial plants and hibernating animals sense naptime is over. Climate change has the potential to disturb the signals that tell dormant vines to get up and going. Changing amounts of daylight alert photoperiodic plants that are sensitive to the relative amount of day and night from one season to the next and in a 24-hour period. The changes in air temperature and the angle of the sun also play vital roles. As the amount of warm air increases, plant hormones and cells in the tips of a plant’s root triggers the plants to send out new growth. In the case of grapevines, the appearance of buds tells watchful winemakers and vineyard managers the cycle of growth and renewal is beginning. Bud break is the first joyful sign the vines are alive.
John Williams, winemaker at Frog’s Leap Winery, notes that timing is crucial for grapevines. He says, “ If a grapevine gets up too early in the spring, its very existence is in peril from crippling frosts lying in wait for its tender young buds. On the other hand, if it decides to sleep in, it may find itself at a competitive disadvantage from adjacent vines eager to grab space in the sunlight. Waking up is one of the most critical decisions the vine will make all year.”
During the long dormant season that precedes new growth, a lot of activity takes place in the vineyard. Vineyard workers are out in the field with pruning shears and typing the vines up for stability. Pruning vines sets the stage for the season’s growth, guiding the vine to grow in optimum directions to capture sunlight and moisture.
After a few weeks of vegetative growth, vines develop bunches of small flowers. Each flower will develop into a grape berry. This is a crucial time since frost can damage the potential development of the grapes. Then, the pollinated flowers drop their petals and form into tiny green bulbs. The plants grow vigorously in the next months and leaf production vies with grape development. Canopy management requires leaf removal, shoot thinning, and other techniques to assure a proper balance between shade, sunlight, and air circulation around each bunch, requiring many passes by workers through the vineyard. Crop thinning or culling imperfect bunches gives grapes left on the vine all of nature’s benefits during the growing season. All grapes are green until the middle of summer, hiding their true nature from all but the trained eye until the development of pigment on the skins in the process called veraison. And slowly, it’s time for harvest, or crush.