Viticulture in Coonawarra

An introduction to climate and geology

The following is a brief overview of Wine Australia Sommelier Immersion Program 2016 session with Wynns Coonawarra Estate vineyard manager Ben Harris in Coonawarra that took place on May 12th.

Although the region has its climactic hazards; spring frosts, rain at vintage time and cooler years that are less than ideal for ripening Cabernet Sauvignon, South Australia’s Coonawarra wine region seems by and large viticulturally blessed. The combination of the unique structure of terra rossa soil over limestone and a moderate climate provide ideal conditions for growing world class fruit.

Coonawarra's climate - ocean influence and cool nights

When most people think of South Australia as a wine region they think of warm climates and ripe fruit. Coonawarra is one of the most southerly wine regions in the state and differs from the status quo with a moderate climate.  Although the region is inland from the coast, it is very flat and ocean currents from the Antarctic easily cover the distance from the coast and are able to cool the vines during late summer afternoons, resulting in warm days and mild to cool nights. This, in combination with consistent cloud cover, allows for a longer and slower ripening season giving the fruit a chance to develop more complex flavours and retain its natural acidity.

Coonawarra geology - a landscape forged over a million years

Australia has some of the world’s most ancient soils and arguably Coonawarra is home to the country’s most famous terroir. The landscape of Coonawarra reflects the revolutionary forces of nature over the last million years. The whole region was under the ocean until the ice age which froze the water into polar ice caps causing the shoreline to recede. The land that rose above sea level after the ice age was limestone.

Coonawarra has three predominant soil types that sit on top of this limestone base. There is the famous terra rossa or ‘red dirt’ which runs in a cigar shape on a ridge along the main highway (it is no coincidence that the Riddoch Highway follows this ridge as carters sought the firmest ground in times past). To the west of the ridge lies the black rendzina soil which are heavy clays, with higher water retention capacity. These rendzina soils can be more challenging in wet, cool seasons as vine vigour may not be contained and large shaded berries with poor colour and quality can result. There is also a ‘transitional’, or brown rendzina, soil which grows vines quite successfully. The podzolic soils to the east of the Coonawarra ridge represent weathered coastal sand dunes. Vines are not grown here, it’s mainly used for forestry although there are vineyards on the shallow sandy loam soils to the east, located between the terra rossa and podzolic soils.

Terra rossa - Australia's most famous terrior?

Terra rossa is by far the most prestigious and expensive land of the region. After the melting of the ice caps exposed the limestone, prevailing maritime winds blew silt from nearby plains creating light clay rich in iron, silica and nutrients. This clay oxidised into the red-coloured ‘terra rossa’ soil that is synonymous with the region today. The terra rossa runs for just 27km, is approximately 2 kms wide and averages 50cm in depth. The soil is calcium rich, which along with the iron oxides, leads to good drainage. The soil pH is neutral to slightly alkaline, maintained by the dissolving calcium carbonates. This restricts the availability of nutrients such as phosphorus, copper, zinc and manganese to the vines. Below the terra rossa is a calcrete capping which is a hard layer of calcium carbonate on top of the less-dense limestone below. This calcrete curbs deep root growth and controls the vines vigour. This restriction is important to the concentration of flavour and distinctiveness of these wines.

The culmination of the factors outlined above gives Coonawarra a moderate climate that prolongs the ripening season and a unique soil structure that restricts water and nutrients to the vines. This results in fruit (in most vintages) that has reached phenological ripeness with great concentration and complexity of flavour whilst retaining high natural acidity. In terms of the region’s Cabernets this translates into wines with medium body, velvety tannins and highly intense aromas and flavours which consist of black fruits and dark chocolate, which are usually accented with notes of toasted oak in the winery. It also means these wines will cellar exceptionally. Tannins and acidity will soft and flavours will move into the tertiary spectrum of leather, meat and Christmas cake.

Sommelier Immersion Program

Established in 2012, Wine Australia created the Sommelier Immersion Program (SIP), an educational program for Australian based sommeliers. In its fourth year running here in Australia, SIP aims to garner a deeper connection and understanding of the diversity of Australian wine and to connect sommeliers with the regions and personalities behind our wines. Wine Australia aims to educate and create a fraternity of Australian based sommeliers that are true champions and ambassadors for Australian wine through this program.

Profile: Caitlyn Rees

Sommelier at Momofuku Seiobo

Caitlyn has been working as a sommelier for the past 5 years. She recently took up an excellent opportunity at the David Chang restaurant Momofuku Seiobo in The Star Casino, Sydney. Caitlyn is half way through her WSET diploma and intended to continue with her studies, ultimately with the goal of becoming a Master of Wine.

Momofuku Seiobo is a 30 seat, 2 chef’s hat restaurant. The degustation menu celebrates Australia’s wonderful produce but is heavily accented with Head Chef Paul Carmichael’s Caribbean heritage.



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