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 Viticulture Climate Soil Natural balance
This initial planting of Chardonnay was followed by Cabernet Franc and Merlot (3.0 acres) in 1984 and Pinot Noir (2.0 acres) in 1996. Viticulture Vines were planted on a 2.5 x 1.2 metre grid, giving 3333 vines per hectare. This is approximately double the density of most Australia vineyards. Behind this decision is Ken's belief that a vine would need to work only half as hard to produce and fully ripen its crop. For example, to achieve a crop of 7 tonnes per hectare at Portree, vines would only have to carry a crop of 2.1 kilograms per vine; whereas at the conventional planting density they would have to carry 4.2 kilograms per vine. Halve the workload - double the quality? With the rows being closer together, it is critical that vine foliage is managed during the growing season. Damage and crop loss due to the tractor passing down the rows would otherwise be substantial. Ripening in such a cool climate would also be hampered. To overcome these problems, the Chardonnay, Cabernet Franc and Merlot shoots are trained vertically and held in that position by sets of movable wires. This is termed 'vertical shoot positioning'. The Pinot is trained to unilateral canes using the Scott Henry system allowing maximum bunch exposure. The bunches, which are always at the lower ends of the shoots, are thus exposed to light and air which assists with ripening and disease management. The lack of shading in the vine canopy results in increased sugar and tartartic acid levels and decreased juice and wine pH. The entire vineyard is managed manually. Hand pruning, training and picking ensures that quality is maximised at every stage. Climate After variety, climate is the most important factor affecting style and quality when growing wine grapes. Warm climates tend to produce 'bigger' wines. That is, wines higher in alcohol, with strong forward fruit flavours. Genuine cool climate wines usually have more elegant fruit flavours and are balanced by firm acidity (see 'Natural Balance' below) and fine tannins. Obviously there is more to climate than warmth/coolness. Rainfall pattern is also important. Ample moisture is desirable at the beginning of growth in Spring, whilst dry Autumn conditions during the final stages of ripening, increase grape quality and harvest the crop at its optimum. It is recognised that the amount of heat received during the growing season is very important. One of the methods of measuring this is temperature summation. This is the most widely used climatic index for comparing regions, despite being complicated by the effect of latitude on day length. Temperature Summation for some Wine Areas
* Source: Jackson & Schuster - Coombe & Dry The vineyard at Portree is at an altitude of 570-600 metres (1700-1800'). The climate is continental - that is, a high diurnal range in temperature and the opposite of most of the other cool wine producing areas of Australia, which have maritime influences. This is probably why comparisons are made to Burgundy and Oregon when it comes to Chardonnay and especially Pinot Noir. For the technically minded, the Mean January Temperature (MJT) averages 17.8C giving a heat summation of around 1150 degree days (HDD). Slightly cooler than Burgundy, but in Australia our higher latitude gives shorter daylight hours meaning the heat is 'collected' in a shorter period - more intense. Rainfall is 850 mm p.a. falling predominantly in Winter/Spring. March/April are the driest months of the year fortuitously coinciding with vintage. The Macedon Ranges altitude, lack of maritime influence and large diurnal temperature range are all part of the equation that contributes to the uniqueness of the wines. Soil Vines thrive in well drained soils. In fact, some wine commentators believe that the intrigue surrounding the range in quality of some Burgundian vineyards situated not more than 50 metres apart, is related to better drainage. The soil at Portree is basalt of volcanic origin from Mt. William, dating back to the Cambrian period 530 million years ago. It is free draining to the extent that the young vines would have been unable to establish without supplementary water during their first two years. The soil also appears to be 'bottomless' as no impervious layers have been encountered that might restrict root growth. Vine roots will extend to a depth of five metres or more if there are no hard clay or rocky barriers to impede them. Soil fertility here is low which helps control vine vigor, thus avoiding the 'all shoot, no fruit' situation that sometimes affects cooler growing areas. In this regard, considerable effort went into choosing the site for Portree. The objective being to try and achieve the best of both worlds. Those of you thinking that science and wine appreciation are drawing too close together, please return to the glass at hand and then on to 'The Wines' page. Check out the Winemaker's Notes Back to top |
