Red grapes at pressing time
The Margaret River Advantage … Versatility
Margaret River has a great reputation for both the short growing season Chardonnay and the long growing season Cabernet Sauvignon. In the world of wine that is most unusual. Usually a particular place will have a reputation for early season varieties, mid season varieties or late season varieties, never the entire spectrum. Why is it so?
What do we mean by ‘Margaret River’?
To the surprise of many people the viticultural region is not focussed on the town of Margaret River which just happens to be about half way between the northern and southern extremities. In fact the Town of Margaret River is to the south of the main centres of viticultural activity. Geographically the Margaret River viticultural region is limited by a line of longitude that separates the town of Busselton from the hamlet of Vasse just a few kilometres to the west. Busselton is out. Vasse is in. This line of longitude is referred to as the ‘Gladstones line’. The region is about 25km in its east west extent. In its north-south dimension the Margaret River region extends from Cape Naturaliste in the north to Cape Leeuwin in the south, a distance of 100km.
In terms of landform the region is by and large upland that is west of a north south fault line. To the west of the fault line the ancient granite rocks of the continent appear. To the east of the fault is a sunkland characterised by sands and clays of marine origin.
In terms of the human landscape the ‘Margaret River wine Region’, includes a large part of Busselton, Vasse, Jindong, Marybrook, Carbunup, Dunsborough, Eagle Bay, Yallingup and Willyabrup all tied administratively to the city of Busselton. In the Shire of Margaret River there are the hamlets of Cowaramup, Margaret River itself, Witchcliffe, Karridale and Augusta.
Many people will be surprised to learn that In terms of comparative area the bulk of the industry and by far the greater number of enterprises is located in the Busselton shire, now called the ‘City of Busselton’, the population having grown to exceed 33,000 souls whereas the population of the Augusta Margaret River Shire is less than half of that figure. The viticultural region we speak of as ‘Margaret River’ encompasses part but not the whole of two local government districts.
The man who suggested that great wine could be made in what might be more accurately described as ‘the Capes Region’, John Gladstones, described the area in his ground-breaking book ‘Viticulture and Environment’ in 1992 in the following terms.
The Margaret River region strictly defined takes in the slopes of the low ridge that extends from Cape Naturaliste in the north to Cape Leeuwin at Western Australia’s extreme south western tip. The ridge comprises granitic and gneissic rocks over which laterite has formed. The vineyard soils are derived either from laterite or from the underlying country rock at lower levels in the valley’s and are found chiefly in the drainage basins of creeks and small rivers running north east or north into Geographe Bay, west to the Indian Ocean and south east into the lower reaches of the Blackwood River.
The area is greatly influenced by the maritime nature of the prevailing westerly and south westerly air stream. This region is the first point of contact, between Southern Africa across the Indian Ocean, and the Australian continent.
Developed commercially for vine growing at the same time as the Great Southern Region, the Margaret River region provides an interesting comparison. Whereas the Great Southern region has average month mean temperatures ranging from about the cooler limit of Bordeaux, down to only a little warmer from the Loire Valley, the established Margaret River and surrounding area in the central and north central parts of the region respectively are appreciably warmer during ripening, than the Medoc but similar to Pomerol and Saint Emilion. Sunshine hours during the growing season and ripening period are marginally more than in all Bordeaux areas and the Great Southern region, whilst relative humidities are intermediate and probably about optimal. Summer and ripening period rainfall totals are very low. Apart from too little summer rain for solely rain fed vines, these are conditions which in Bordeaux would typify a great year. They doubtless help to account for the intense flavour in red wines and the intensity of flavour and varietal character which are features of Margaret River wines. A notable feature of the Margaret River region as a whole has been the good adaptation of Bordeaux grape varieties.
John Gladstones places large store on the origin of the air streams that flow into the region that influences ripening temperature, secondly the humidity and rainfall distribution thirdly the rock and soil types influencing water holding capacity and finally sunshine hours. As a climatologist, a plant breeder, a biologist and a wine drinker he is interested in the determinants of the performance of the vine as a fruit bearing plant Nd above all the origins of flavour.
The latitude comparison
Below we see a landscape in Morocco. This is the same 33.5°S to 34.4°S latitude in the Northern Hemisphere as Margaret River in the Southern hemisphere. The Moroccan landscape is reminiscent of the Western Australian wheat belt. In North America the comparative west coast latitude is that of Los Angeles, at the southern extremity of viticultural activity that stretches as far north as the 49° parallel of latitude. On the basis of its latitude we would expect Margaret River to be a very warm grape-growing region, perhaps too warm.
This simple inter-hemisphere comparison is misleading because the southern hemisphere is two thirds water whereas the northern is just one third water. Consequently summer temperatures are much warmer at higher latitudes in the northern hemisphere while winter temperatures are much cooler than Margaret River. The vine is a summer growing plant. Warm summers in the northern hemisphere allow viticulture to thrive much further pole-wards than is possible in the southern hemisphere. The limits of viticulture in the southern hemisphere are found at about 45° south in both Central Otago and Patagonia, both located in the rain shadows of high mountains with less cloud and warmer summers than coastal situations at the same latitude. In Australian terms we go no further south than Hobart that is at latitude 42° south.
The further away from the equator the larger the swing in temperature between summer and winter. It follows that the length of time that the vine is in leaf shortens as latitude increases. High latitudes demand grape varieties that have short growing seasons and these varieties exhibit ‘early maturity’. If the season of leaf activity is too short sugar levels may not reach that required for wine stability, at least 12%. However, in the grape vine, flavour maturity is independent of sugar levels. So grapes can be flavour ripe with low sugar levels, low pH and well conserved fruit characteristics even at high latitudes. This is so because the fruit ripens under optimally cool conditions. High latitudes provide a true ‘autumn’ where deciduous plants are programmed to mature their fruit as they lose their leaves.
By contrast in warmer climes with a longer growing season, short season grape varieties can ‘mature’ in the sense that sugar levels are adequate but the fruit exhibits low acidity and little in the way of attractive, mature berry flavours. Frequently one sees the flavour of ‘raisins’ and ‘green fruit’ in different parts of the same vine and across the vineyard.
Ripening period temperature comparisons
The difficulty that an Australian viticultural region must face is the tendency for hot dry winds to blow from the interior of the continent during ripening. Since the air flow is predominantly from west to east the westerly side of the continent has an advantage. Cooler air off the sea means less flavour damaging heat. Even so, with the passage of the high pressure cells from west to east, a hot wind must blow from the east for a couple of days, every ten days or so. The south western corner of the continent is least exposed to these climatic insults.
Within the 100km north-south extent of the Margaret River region there is a markedly increased incidence of warmer temperatures as we travel from south to north. For the earliest varieties like Pinot Noir and Chardonnay that ripen between the last week in February and the first week of March the hour degrees above 22°C experienced in Karridale is about half that experienced between Witchcliffe and Margaret River which is in turn about half that experienced in Dunsborough which is in turn one tenth of that experienced near Perth only 250 km to the north of Dunsborough. As a result the Swan Valley is one of the hottest ripening regimes on the globe while the southern extremity of the Margaret River region can be favourably cool, just 300 km distant and in terms of averages, cooler than Bordeaux. This compression inevitably brings with it seasonal variations that are most influential in February and March and much less so in April.
The late varieties like Cabernet Sauvignon are picked three weeks later in Karridale (late April) than in Dunsborough . Ripening temperatures for late varieties in Karridale are 1° C cooler than the Medoc in Bordeaux. A similar situation exists in Coonawarra, the Limestone Coast in South Australia and in southern Victoria but the risk of damaging heat is greater than it is in the extreme south west of Western Australia.
The upshot is that Margaret River is the most versatile wine region in the globe with an extraordinarily long growing season (low latitude) and a relatively cool ripening period (the maritime influence) making it possible to produce flavoursome wines from early through to late grape varieties. This is the strength of the region. It has great potential for flavour conservation and is extremely reliable. In thirty years of grape growing only the 2006 vintage (very cool and late) produced Cabernet Sauvignon that was uncomfortably green and herbal. This is in fact the tendency of the variety. By contrast the Petit Verdot of 2006 ripened very well. Petit Verdot an extremely valuable variety with a potential as yet unrealised.
So, Margaret River has a rich choice in terms of the flavours available from a great many grape varieties. I would expect that the varieties that we esteem today will be replaced by others with less aggressively green and more appealing flavour characteristics in the future. What we grow today is the result of our British cultural heritage. What we grow is due to the English familiarity with the wines of France, Spain and Portugal. There are grape varieties of interest in Italy, Greece and Central Europe that we know little about.
Viticultural practice at the cool margin
At the cool margin skill and understanding is required. If one adopts the standard vineyard design incorporating vertical shoot positioning on wide rows and combines this with irrigation and prevailing soil management practices, then grape flavours tend to be uncomfortably green and herbal. Many growers have not persisted with late varieties south of Witchcliffe. To do the job, one needs old fashioned hand management of vines, dispersed shoots, hard pruning, crop thinning, high leaf area to fruit ratios, many working leaves followed by hand harvesting. It’s labour intensive, especially after you cover every row with net to protect the crop from birds. But the results justify the effort.
The Achilles heel of any low latitude maritime climate so far as viticulture is concerned is the warm winter and staggered budburst in spring. This leads to staggered shoot development leading to extended flowering, staggered fruit set, carrying through to differences in fruit maturity from one part of the vine to the other. In the wine this means ripe and green flavour present at the same time. To combat this, it is desirable to have a long cool period of slow ripening to allow the laggard bunches to catch up. Hard pruning and low cropping regimes assist because the vine stores carbohydrate in its root system and permanent wood. It’s better to operate the system well within its capacity rather than to be struggling to bring the grapes to maturity leading to even more staggered budburst in the following year.
Margaret River has an enormous advantage in terms of versatility. It has an extraordinarily long growing season and cool temperatures in the months where the fruit matures. However, to realise the best results one must understand the viticultural influences on fruit maturity and design ones vineyard and management regime accordingly. The standard Australian pattern of large tractors, wide rows and narrow canopies will fail to yield appropriately ripe fruit all too frequently.
The ‘Capes Region’ can do well with a very wide range of grape varieties but you need to be aware of what you are doing. It’s just as easy to produce rubbish in Margaret River as anywhere else on the planet. St Georges Terrace farmers beware. In 2009 we had the interesting experience of producing a Shiraz wine from fruit that was rejected by a global corporation early in the growing season….the grower cut the irrigation off with the intention of pulling the vines at the end of the season. The fruit was going to waste. We took it. The result was a wine with powerful ripe flavours and considerably less ‘green flavour’ than had been seen in the past. Removing the water was the key to the improved result. Green flavour had been rendering the wine unpalatable year after year under a regime of constant care, fertilization and irrigation in an effort to keep the leaves green and the plant ‘apparently healthy and productive’ and for a time this led the Global Corporation to maintain the contract. In the end they realised that the wine was no good and they did not have a clue what to do. The task had been seen as simply finding enough cheap fruit to meet a price point. This wine company is run by accountants and the winemakers either knew little about the origins of fruit quality or had insufficient influence to call the shots. The vineyard was owned by absentees who were professionals in a different field. It was a case of the blind leading the blind, direction by committee. The irony is that in abandoning the vines circumstances improved and the vines responded by ‘producing the goods’.