July 29, 2012
So far, this year's weather has been pretty much perfect. Lots of days in the 80's and low 90's, lots of nights in the 50's. Very few days where the highs were in the 70's, and only a few where we got above 95. Having daily highs range between 80 and 95 is important because most grapevines won't photosynthesize at temperatures above 95. Instead, they close the pores in their leaves and try to conserve moisture in self-defense. It doesn't always work; too many days above 95 (or even a few days too much above 95) and you start to see berries turned prematurely into raisins, as grapevines sacrifice some of their potential crop to preserve their overall health.
Given the relatively ideal conditions, it shouldn't be surprising that we're starting to see veraison earlier than in the last two notably cold years. Veraison is a French word that marks the point in the year where fruit stops accumulating mass and begins to accumulate sugar. This change manifests itself in several ways, but most visibly in the beginning of color change in red grapes from green to red and in white grapes from vivid green to a softer, more yellowish hue. Viticulturist Levi Glenn caught some early veraison at the top of our Syrah block early this week. Syrah, almost always our first red grape to be harvested, is first off the blocks as usual:
As a rough rule, we figure six weeks between veraison and harvest for most varieties. This suggests that we'll start to harvest Syrah (as well as Viognier, which is also starting to go through veraison but whose changes don't make for very exciting visuals) at the very beginning of September. Starting in early September is normal for most of the world, but for us it's just a touch early. Our average start date since our first vintage (1997) has been September 9th. But that doesn't catch the full range of possibilities; in the last decade, we've begun harvest the last week of August twice, the first week of September three times, the second week of September once, and the third week of September four times, including both of the last two years.
Syrah wasn't the only grape in which Levi found signs of veraison. Mourvedre, although it is typically our last grape harvested, tends to show veraison relatively early, and we've learned to expect ten weeks between its veraison and its first harvest. A Mourvedre cluster, just starting to turn color, also from the top of its hill:
The weather over the coming weeks will have something to say about our harvest date. But veraison does provide a pretty reliable gauge of where you are. And the combination of yields (about average) and weather (warm but rarely hot, and consistent) suggests we're looking at a year very much like 2000, 2002 and 2007. That has to be a good thing.
[For those interested in more detail on the veraison, check some past veraison posts. For more on the chemistry, out the post from 2007. For photos of the different red grapes mid-veraison, see the post from 2008. For more on comparative dates on veraison over recent vintages, see the post from 2011.]