The continental climate of the Duero usually translates into very cold winters that have a direct influence on the vineyard. We explain the beneficial effects of low temperatures and the “below zero” ranking in Abadía Retuerta.
The harsh climate of the northern Castilian plateau is a familiar topic in daily conversations during the winter and even more so in the conversations of our visitors. Not for nothing a popular saying in Castilla y León points out that in Burgos there are only two estaciones (a word that means both season and station in Spanish): the winter’s and the train’s.
In the neighbouring province of Valladolid, where Abadía Retuerta LeDomaine stands, frost has been a constant in recent weeks. On some days the frost has not disappeared for much of the morning due to the presence of a stubborn and persistent fog that is often with us at this time of the year.
Cold weather and sleeping vines
From the end of the harvest until we start pruning in February, the vineyard is left alone. We let nature run its course; the leaves fall and the plants enter their dormancy period. It is now when the sap descends and the plant enters a state of hibernation.
The beneficial effects of the cold on the vines are many. The most important ones have to do with its antiseptic action on fungi or insects that can cause diseases in the plant. In fact, there is a direct relationship between particularly cold winters and the lower incidence of powdery mildew (an endemic disease here and in most Spanish regions) while the plant sleeps. The lower the winter temperatures, the healthier the vines will be in spring.
On the other hand, when a cold winter and a cool spring are combined, the soil temperature drops, which can lead to a later budding. This suits us well in the Duero as this area is at great risk of spring frosts —they were particularly devastating at the end of April 2017 because the vineyard cycle was somewhat advanced. “At a depth of 60 cm, the soil temperature at this moment last year was 6.4º C; this year it is two degrees lower”, explains our winemaker Ángel Anocíbar.
Below zero, but how far?
According to our data of minimum temperatures going back to 1967, the lowest temperature registered at Abadía Retuerta is -20º C in the winter of 1971. In that year the thermometer dropped to -16º C and -15º C, the lowest temperatures we have had in the last 50 years. In 1985, temperatures also dropped to -15º C.
In such conditions, plants begin to face a serious risk to their survival. This explains why in grape-growing regions with extreme climates, such as in Canada, they either bury the vines in winter or plant producer hybrids (crosses of wild and vitis vinifera vines with greater resistance to the cold) directly in the soil. Abadía Retuerta hasn’t escaped some bad experiences either: the cold has been known to ruin some young vines that are more sensitive to external factors.
It is significant (see following chart) that, with the exception of the 2001 harvest when temperatures dropped to -14º C, the 2000s suffered less extreme winters. For Ángel Anocíbar, it is yet another indication of climate change.
A word of advice to those of you who visit us at this time of the year: wrap up well to keep warm. We may not be at -20ºC, but the mornings are certainly cold.