| Terroir Australis: why some areas grow better wine than others | | | | By: Darby Higgs |  Page 1 of 2 next >> |
Terroir is a word that gets bandied about a lot lately. You need to know what it means if you want to know if the speaker or writer knows what she or he is talking about.
Terroir is a French word which does not translate directly into English. It is derived from “terra” the Latin word for earth that gives us English words such as terrain and territory. But terroir is a word that has much deeper meanings than just earth.
The best definition I can find is that it refers to the totality of the environmental factors which influence viticulture at a particular site. The obvious factors are soil and climate, but it is worthwhile digging a little deeper; topography and hydrology are also important.
The French have developed the idea of terroir in tandem with their Appellation Controllee system. Terroir is based on the idea that great wines can only be made in those areas (mainly in France) where there is a long tradition of winemaking. The vines, and even the winemaking itself, are integral to the natural environment.
Like most deciduous plants the grapevine is most at home in the temperate zones. A distinct annual seasonal pattern seems to be required.
Climate is the difference between grapes capable of making high quality wine, and those that can only just pass muster. When discussing the different characteristics of wine regions the first question we need to answer is “Is it a cool or warm region?”
The overall temperature data of a region is often represented by the heat summation scale. The number of ‘degree days’ of a region is calculated by adding up the amount that the temperature exceeds 10 degrees Celsius each day throughout the vine’s growing season. Heat summation doesn’t give you the complete picture but it is a good first check to see which grape varieties if any are suitable.
The heat summation for a few Australian wine regions are given below
Hobart, Tas 1017
Launceston, Tas 1156
Portland, Vic 1204
Healesville (for Yarra Valley, Vic) 1251
Eden Valley, 1309
Ararat (for Great Western, Vic) 1335
Coonawarra, SA 1337
Pemberton, WA 1394
Canberra, ACT 1424
Mornington, Vic 1427
Geelong, Vic 1457
Barossa Valley, SA 1525
Margaret River, WA 1529
Rutherglen, Vic 1567
Bendigo,Vic 1579
Strathalbyn, SA 1592
Clare, SA 1594
Young, NSW 1649
Mudgee, NSW 1704
Stanthorpe, Qld 1704
Cowra, NSW 1719
Merbein (for Mildura, Vic) 1753
Berri, SA 1756
Griffith, NSW 1756
Perth (Swan Valley) WA 1818
Jerry’s Plains (Hunter Valley, NSW) 1851*
These figures should be seen merely as a starting point. The actual growing conditions on individual sites can make a huge difference. For example north-facing slopes will be warmer, the local topography moderates the effects of hot winds, sloping sites are less prone to frosts, and so the list goes on.
The heat summation scales do not take into account other factors considered important, such as the daily variation in temperature, the number of sunshine hours and the relative humidity. Selecting a good site for a vineyard takes all of these factors into account.
Once a site is selected care is needed to use appropriate grape varieties. The time taken for grapes is a characteristic of different varieties. For example in Rutherglen early varieties may be picked in mid February, while later varieties will need until the end of March.
In cool areas only early ripening varieties are feasible. Late ripening varieties will not ripen at all if planted in a cool area.
Conversely in hot areas late ripening varieties are preferred. These will ripen slowly in the autumn. Early varieties can be grown in warm climates but as the grapes ripen in the hottest part of summer a balance between acid, sugar, flavour compounds and tannins is impossible to achieve.
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