Winemaking in an El Nino Year
A Google news search for El Nino’s effect on vineyards generates tens of pages of opinion articles speculating on if and how the big winter will contribute to the quality of the 2016 harvest.
As always, the media is stirring up concern regarding the impact of heavy rainfall on grapevines in articles such as Eater’s, which puts a borderline negative spin on the heavy winter.
During winter, grapevines are in dormancy. They have or are in the process of turning the carbohydrates accumulated from photosynthesis into starch, stored in the rootstock. They were fast asleep until just a couple weeks ago when rain in the forecast all but disappeared. The sun came out and it was actually warm. Our plum tree in the backyard now has a full set of blossoms on it. That’s really great and pretty and all but — it’s February! Any multiple storms in a row can wipe out those flowers and least be said there will be no plum pie this year.
Considering the weather from the past couple of years, this is nothing new. But timing is everything. Combining a warm winter break with a few days of sunshine thoroughly confuses the vines. Just last weekend, we saw the proof at Ridge Vineyards, famous for the Monte Bello site, high up on the Santa Cruz Mountains. Tiny buds had appeared the week before. And here we go, the 2016 growing season has begun.
Most articles and blogs written by or featuring winemakers are positive and hopeful for as much rain as possible until Spring when good and stable weather is imperative for fruitset quality, the first and often most import determinator of the vintage quality. If you can remember in 2014-15 we had a very dry winter and it appeared Spring was going to be the same, until we had completely imperfect timing of a storm exactly during flowering. The rain, however light, washed away the delicate but important flowers on the vines, “shattering” the future clusters. Not all vineyards were affected, of course, but it was significant and the crop was lighter because of it. In a dry Spring without frost, clusters will fully flower before progressing in their development to form round, even clusters. It is only with heavy rains or frost in the Spring that the yield and quality can be severely compromised.
And truthfully, California receives so much sun in an average year that vines will overproduce for the desired quality. Many premium wineries will actually drop fruit once the clusters start rapidly developing. Instead of producing six tons per acre, the desired yield, depending on the varietal – will lower to four or three or even lower. Of course, vines will plateau production for several years and then as they age produce less and less. By dropping fruit, the vine puts more energy into the “survivors” thus producing more vibrant, concentrated fruit.
Brian Talley, from Talley Vineyards on the Central Coast has a great blog post worth reading about El Nino‘s impact on this region of California as well.