Anther fully extended

The Sex Life of Grapes

Flowers are every­where in the spring in Northern Cali­fornia. On the sides of roads, in the cracks of side­walks, between the rows of vines, clutched between your teeth. Roses are in full blush, patches of wild poppies duti­fully perform their open-close routines with the rising and setting of the sun and the slutty manzanita bushes expose their sticky stamen to hordes of humming­birds. The vines too are flow­ering, although it is a less dramatic affair “compared with many other plants,” writes Jancis Robinson, MW. “The vine has unat­tractive small green flowers and the flow­ering process in the vineyard is so notably unspec­tacular that it is likely to be missed by the casual observer.”

Up until now, the clusters we’ve seen have been exactly those small green flowers. This week, they started to open up. The flow­ering process can take weeks — or days — depending on the weather. The sequence of events goes some­thing like this: the indi­vidual flowers open, the cap, or calyptra, which fuses the petals together, is shed, releasing the pollen which then fertilizes the ovary, forming seeds and ulti­mately grape berries. “Most wine grapes have perfect, or hermaph­ro­ditic, flowers — that is, with well-developed and func­tional male and female parts,” says Robinson.

Flow­ering, as you can imagine, is an important time in the vineyard. If it’s too hot, too cold, too wet, too windy, those flowers will simply not set and will instead blow off and fall to the ground, a process known as shatter.

The key for all farming is moder­ation,” says Tegan Passalacqua, wine­maker for Turley Cellars. And flow­ering time is no different: “You don’t want the highs and the lows.” This week in his zinfandel vineyard in Contra Costa, Passalacqua saw what he describes as “the fastest I’ve ever seen anything flower, ever.” Six days. The same vineyard last year took nearly three weeks thanks to rainy and windy weather. “When things flower quickly you get great fruit set and cluster weight,” says Passalacqua. (Even under perfect condi­tions only about 30 percent of flowers will become berries.)

Turley’s St. Helena vineyard has just started flow­ering and in Amador County, where soil temper­a­tures are moderated by snow melt and the vines are noto­ri­ously behind, has yet to begin. Passalacqua, and grape farmers every­where, are hoping for calm air, moderate temper­a­tures (the mid-80s will do) and of course, no rain. We are happy to report that his week’s forecast (for Napa Valley, at least) is exactly that.

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