Climate and weather
TThe Bordeaux climate could be classified as oceanic-temperate, with moderate temperatures in both winter and summer. The nearby Atlantic Ocean has a major effect on the difference between day and night temperatures. Cool nights in the summer help to keep acidity levels in the grapes high. Acidity also helps to ensure that the grapes stay in healthy condition.
As the weather warms up in March or April the buds on the vines start to burst. At this time of the year frosts can be a problem. Annual rainfall is about 700-800 mm. Summers are often sunny and dry, the weather is normally very pleasant, although temperatures may rise to over 40 degrees Celsius!
Long spells of rain during the later stages of the growth cycle is not desirable because the roots carry water directly to the grapes, thus diluting the final wine. However, this depends on the type of soil. Gravely soil allows rainwater to drain very quickly, whereas clay-based soil retains water. At this stage, moist soil and humid growing conditions can encourage nearly ripe grapes to rot.
The ideal weather for harvesting is dry and slightly windy. The wind helps evaporate the morning dew and the grapes can be gathered in perfect condition. Moisture and rain not only cause grapes to become diluted, but water can also cause grey rot.
Great wine can only be made from first class grapes and so quality-conscious viticulturists try to do everything they can to avoid rot and produce top quality grapes. Hand picking will allow us to process only the healthy grapes. We will also go through the vineyards once or twice to make a “green harvest” – in other words cut the excess unripe bunches during July / August. By reducing the crop we will insure that the grapes, which have been left on the vines, will ripen earlier and uniformly. There is also a risk that if the bunches are touching each other, then water will stay around the grapes and this in turn will cause rotting. To avoid rotting we will also remove the leaves from around the bunches in order to let air circulate freely. For white grapes we will not leaf pluck the vines on the hot sunny side but for the reds some sun will help ripen the grapes faster.
Soil and Geography
CChâteau Carsin is located in the “Côtes de Bordeaux”, literally “the hills of Bordeaux”. These hills run along the eastern bank of the Garonne upstream from the city of Bordeaux. They are essentially composed of clay-limestone soil, with gravel topsoil. A high concentration of clay is best suited for growing Merlot grapes. Earlier on we were particularly interested in Château Carsin’s gravely soil, because this is ideal for Semillon and other white grape varieties, which were then our main priorities. Now we also plant Merlot vines in some of the more gravely parcels as well as experimenting with old Bordeaux red varieties such as Malbec, Carmenere and Petit Verdot.
Soil structure is important in regulating water uptake. Our vineyards have clear differences in soil composition and these all play a part in the final blend. Clay will produce heavier and stronger wines. Gravel on the other hand will give the grapes ripeness and more intensive aromas.