Another growing season has come and gone in the Texas Hill Country. It is time to review what the grape vines endured this year, and I am sure more than a few of you will be intrigued to know how that wet spring affected the vineyards.
The following graph shows this year’s cumulative precipitation from the Dripping Springs Weather Station which we use to cover the Salt Lick Vineyards, which accounts for a significant amount of our grapes. As can be seen right from the beginning, it rained more than the long term average. In fact, on May 29th the accumulation of rain was almost twice that of the average. Moreover, that month was the wettest month on record with an outstanding 10.82 in (275mm) of rain, which, also, was the case state wide. It actually rained 2 out every 3 a days in May. Then, June came and added a more humble 3.04 in (77mm) amount of water and unexpectedly, it stopped. There was no rain in July and August, except for the 0.02 in (0.5mm) on August 16th to be exact. It was like someone had closed a valve, going from a very wet season to a very dry one.
One hundred miles Northwest of Driftwood the case was a bit different. At the Brady Weather Station, which we use to cover Certenberg vineyards, another very important source of grapes for us, an above normal rain pattern occurred only from May on, although of a moderate magnitude. As it can be seen, it rained two thirds of the volume in Dripping Springs.
Now, what is the effect of these rains on grapevines? Well, there are stages during the season when plants need to grow and develop and times when they just need to concentrate their efforts on the clusters. Below is a scheme of the phonological stages of vines (Adapted from Eichhorn and Lorenz (1977) and Lorenz (1994)).
From stage 1 to 33 they need to expand their shoots and develop. After that, which is marked by veraison (the change of color of the grapes), vines simply need to stop growing and divert photosynthesis production from new tissue to grapes. This simple change in behavior is one of the most important elements which predicts the quality that follows.
The onset of such a phenomenon, also considered the onset of ripening, is very well aligned with temperature and the availability of water and nutrients. If the vines experience too much water and nutrients, then, the more difficult it is to accomplish a good ripening period. This is why it was very important to have that dry period starting just before veraison this year. The plants had more than enough water to grow when it was needed the most and scarcity when it was not needed. In fact, it became so dry we had to irrigate the vineyards, in order for them to survive and do well, which is a standard summer practice.
Having said that, this season was a good opportunity to see how different vineyards or even small patches within vineyards responded to such a volume of rain. The picture to the left shows a vineyard that pretty much enjoyed the excess of water. The light green color at the top of the canopy and how dense it is give away the fact that they were using the excess water and nutrients for canopy growth (which doesn’t participate in the actual grape development/winemaking). Some leaves inside are so shaded they turn yellow due to the lack of light.
At the same time, there are other sites where the excess water was removed through drainage or superficial run off, and the plant got to “taste” just a bit of it, showing a better balanced looking canopy like the picture to the right.
In this case, the plant shows a more transparent canopy, no growing shoots, even though this photo was taken the same day as the picture above. Both are of the same variety, Tempranillo, and are not located very far from each other. So, under the same weather conditions, which includes temperature, rain, radiation, wind and relative moisture (again to be exact), one variety can show diferent performance depending on the characteristics of the soil where they are planted.
The table below shows the Growing Degree Days (GDD) accumulation zones as described by the two authors. The numbers indicate the summation of daily average temperatures minus 50ºF for a period of 7 months. I showed this scale last year, but I think it is good to refresh the context. This year, counting from April to August, there were 4,388 GDD accumulated in Dripping Springs, which is enough to fall into Zone V in the table, which is usual, by the way. The fact that the scale includes a longer period (October included) addresses the authors’ opinion about how correct GDD are in predicting plant growth. Because, at the end of the day, we see varieties being harvested at an equivalent heat accumulation index in the Texas Hill Country as compared to other cooler regions where this system was once established. So, more important than the growing season length is the actual number of Degree Days accumulated.
All in all, this season was a mere 2.1% and 4.3% warmer than last year and the long term average, respectively, (again, this is until August). This is why most of the varieties kept their usual harvest dates within a reasonable range. The one that escaped our forecasts was Tempranillo. It was somehow sufficiently efficient enough to be ready to be harvested some 11 days before last year. So, August temperatures do not even count in this case. Since it was harvested on July 31st , we can say that it needed 3.268 GDD to reach ripeness, which is obtained after taking August out of the sum.
Notwithstanding rains stopping at just the right time, it rained so often during the growing season, that it was a challenge to keep up with the scheduled sprayings. This affected some canopies in general during that rainy period, but they recovered a healthier growth later in the season. Other than this minor blip, the grapes made their way to the winery in very good condition.
Tempranillo, Salt Lick Vineyards – As described above, Tempranillo beat even Chardonnay as the first grape variety within our portfolio to be ready for picking. The practice this year was to segregate the field so that the first-picked fruit would come from the most evenly-ripened plants as possible at one time. This allowed for clusters of similar ripeness being fermented at the same time. All is looking great so far; bright color and nice concentration is what we see at these early stages. Also, after a year of no fruit (in 2013) and a recovery year last season (in 2014), we finally had enough crop to make up for this much sought after wine.
Chardonnay, Certenberg Vineyards – We had a nice crop, harvested at a similar time in the past, and good flavors is what best describes this year for this variety. We separated the best area of the vineyard for our Barrel Fermented program, and the aging wine will stay on its lees for a long while until next summer, at least. The other portion of the Chardonnay was tank fermented on its lees, un-oaked and is a delicious wine.
Sauvignon Blanc, Mesa Vineyards.- Lovely fruit this year. We got it at a very right ripening time with just about 22º brix in the tank. You would have loved to taste it when fermenting, it was fantastic!, but the wine is even better. Great aromas and an even better mouth feeling. We’re hurrying to get it out quickly because I know there are several people just waiting to get this one by the case and let me tell you, they won’t be disappointed.
Syrah, Salt Lick Vineyards. This year the Syrah was fermented on its own, because it was ready just a bit before the Grenache. Very dark, velvety and concentrated is the wine, and it will be the main part of the future GSM from this year, for sure.
Mourvedre and Grenache, Salt Lick Vineyards. This season the Mourvédre and Grenache ripened at the same time and a bit earlier than last year. Maybe, the Grenache was the one most affected by the rains in May, because there were clusters that had visible lower color content when compared with others. So, we decided that it was a good opportunity to make a Rose out of it. Hence, we reserved a bit to this purpose and left the rest to ferment with the always consistent Mourvédre. The Rose is looking very promising, and we are working against the clock to have it ready as soon as possible.
Sangiovese, Salt Lick Vineyards and Tahzii Springs Vineyards.- These two vineyards had a low crop this year, and, so, we fermented them together, since they are only 14 miles away from each other. Interesting notes on the nose and a silky mouth feel make this wine a good blending option for our recently released blend of this variety Sangiovese with Cabernet and Merlot for a “Super Tuscan” expression.
Merlot, Certenberg Vineyards. Merlot was harvested only 2 days before last year’s harvest. This grape pleased us again with an outstanding performance. Very balanced juice and deep color reflects its great ability to adapt to the climate and an even better site, which is completely rain proof, sort of speaking, because of the soil’s great drainage condition.
Cabernet Sauvignon, Certenberg Vineyards. So, we now look to Cabernet Sauvignon the king of all grape varieties. No wonder this is the most famous variety of all. This year Cabernet came in an incredibly balanced condition/with a book-like description: Brix was just above 24, pH right on 3.79 and a TA of 6.15 (g/l tartaric, for those of you for whom these numbers don’t mean a thing, sorry, but, you’ll have to believe me).. Again, we’re witnessing the effect of a very good site here that allow plants to glide through different kinds of vintages and still get the best results from these varieties. In the tank the just-made wine shows an attractive color and beautiful aromas. It is almost ready to go into barrels for ageing for over a year, but it looks just wonderful now.
Finally, this vintage is going to record in history as being the one when our 7 year long drought came to an end and two of our major Colorado River reservoirs, Travis and Buchanan lakes, finally came up from historic lows. The wet spring made us anticipate a challenging year, but the rain stopped right when it needed to stop, and nature gave us splendid weather during the ripening period. So, this extraordinary potential portends another great year for the Hill Country.
PS. More about Growing Degree Days (GDD).
For example, if the average temperature in May is 74ºF the accumulation of GDD for would be:
74ºF – 50ºF = 24ºF, and then,
24ºF x 31 days in May = 774 GDD for that month. The same is done on the whole Apr-Oct period in order to get the total GDD of a particular area.
It is assumed that below 50ºF plants stop growing metabolism, that’s why GDD is considered an accumulation of plants active heat and helps quickly describing an area in terms of temperature. It is not meant to be final as there are other more complex models that take a number of variables like latitude, humidity, winds and more, but it’s a simple and easy tool to use.
Eichhorn,K.W., D.H. Lorenz. 1977. Phänologische Entwicklungsstadien der Rebe. Nachrichtenbl. Deut. Pflanzenschutz. 29, 119-120
Winkler, A.J., J.A. Cook, W.M. Kliewer, and L.A. Lider. 1974. General Viticulture. 4th ed. University of California Press, Berkeley.
Jones et al. 2010. Spatial Analysis of Climate in Winegrape Growing Regions in the Western United States. Am. J. Enol. Vitic. 61: 313-326