Climate and Soil
Making great wine in McLaren Vale requires an intimate understanding of the many factors that affect grapegrowing. These factors include climate, altitude, aspect, soil and geology. While this holds true for any wine region, the diversity of all of these factors within the borders of McLaren Vale demand studious attention and a sensitive feel for the land. Multiple generations of the Osborn family have worked the same plots of land, sharing insights gained over many decades.
Climate
McLaren Vale's climate is of the Mediterranean type: warm dry summers and cool wet winters, with low relative humidity and relatively high evaporation. In McLaren Vale, the risk of rainfall or frost during the harvest period is rare and this is one of the reasons why the region is such a marvellously predictable place to grow grapes and make premium wines. The proximity to the sea is one of the biggest influences on the climate of McLaren Vale as well as the Lower Mt Lofty Ranges which form the Sellicks Hill ranges and which border McLaren Vale to the East. The result is that hot summer days are moderated by cool westerly, southerly or easterly breezes off the surrounding ocean, and also the 'Gully Winds' from the Hills. This makes for a prolonged ripening period during which time the grapes accumulate flavour and intensity. (and they help cool down the vineyard workers!)
Having a 'Mediterranean' type climate means there tends to be a smaller temperature variation. The average January temperature in McLaren Vale is 21.7 degrees C. Annual rainfall is anywhere from 650-700mm. 150-200mm falling between October and April, which means that rainfall is winter dominant, though we do get some in the growing season. There are numerous microclimates within the region, however, determined by variations in soil type and altitude as well as the various geological landforms. This means we can make wines using fruit from these different microclimates to add complexity to our blends.
Soil and Geology
There are a large number of soil and geology types evident across the McLaren Vale region which provides opportunities for adventurous grape growers. A Geology map that was ten years in the making was published in 2010 and it provides a greater understanding of what lies beneath the surface. McLaren Vale was originally a glacial deposit which explains the huge diversity in age and type of the geology and soil. Some of the younger sand and sandstone formations are dated at 500 million years of age with some limestone, quartzite and clay aged between 500 and 750 million years of age. This greater understanding has proved to be a great resource for curious winemakers and was the impetus for more serious discussions about defining the sub-regions of the area.
Altitude
d'Arenberg grows and sources grapes from vineyards all over the McLaren Vale region, with a focus on grapes from the north and north eastern corner. The region itself rises from sea level to approximately 220 metres above sea level in the north, on the rise to the Mt Lofty ranges. The higher areas are much cooler than the low lying vineyards and generally make a more elegant wine, particualrly when sourced from the sandy soils of the Blewitt Springs region. d'Arenberg has released a number of wines that express how these environmental relate to flavours in a glass. These unique wines can be found in the Amazing Sites category and include sub-region Grenache wines and a range of single vineyard Shiraz.