Top Menu

Viticulture

Terrior

Vineyard sites are chosen because of their suitability to particular grape varieties or due to the style of the wine that the winemaker desires. With commercial wines, large flat sites will be chosen to aid with easy mechanical harvest. With premium wines, the vineyard will be chosen based on its own unique ‘terroir’ or sense of place. Terroir is a French term that describes the interaction of the climate and soil and how together, they influence the vineyard and the wine.

1. Climate

a. Type
Wine regions can either be classified as cool, warm or hot. Cool climates tend to be lighter in body, more elegant, higher in acid and lower in alcohol. Warm to hot climate wines tend to have stronger fruit flavours, riper tannins, more alcohol and less acidity.

b. Meso and Microclimate
Different sub regions within the broader region will have their own unique mesoclimate due to differences in slope, aspect, altitude, exposure to sunlight and so on. These variations from the broader macroclimate create the vineyard’s unique character. Furthermore within a vineyard, smaller microclimates exist, perhaps due to windbreaks, an area of heat giving stones or uneven pruning within the vines, thereby creating differences within the vineyard that the viticulturalist needs to take into account.

c. Continentality
Continentality measures the average mean temperatures between the hottest and coldest months. A continental climate is found in inland regions and tends to have a wide temperature variation between day and night. Grape maturity is slowed during the cool of the night, which can help create more complex characters in the grapes.

A maritime climate is found near the ocean and has a smaller temperature differences between day and night. Maritime climates that are not too cool have the advantage of a long autumn period with optimum temperatures for ripening.

d. Other climatic factors
Rain, hail, frost, humidity, wind and extreme temperature variations also affect the overall quality and yield of the grapes, creating a variation in the annual vintage conditions.

i. Rain
There needs to be enough rain to provide adequate water to the vines. However excessive rain in summer and spring increases the risk of disease. Heavy rain can also cause the berries to swell, damaging them. It can also make mechanical harvesting impossible due to boggy soils.

ii. Hail
Hail is damaging at any time during growth and if experienced close to harvest, the grapes may all be destroyed.

iii. Frost
Spring frost will influence budburst and decrease the number of grape bunches formed, lowering the yields.

iv. Humidity
Excessive humidity increases the incidence of fungal disease, which in turn can increase the need to use chemical sprays in the vineyard.

v. Wind
Wind can help to ventilate the vine canopies, helping to minimize disease. However excessive winds can damage young shoot growth in spring and reduce vine growth and yields.

vi. Extreme weather conditions
Excessive heat, especially during summer or harvest can cause berry damage and result in significant losses in the crop level and quality.

2. Soil

Soil plays an important role in the choice of vineyard site due to its water permeability, nutrient levels and its chemical properties. A grape vine will grow the best when its requirements for nutrients and moisture are fully met. A soil should be able to supply moisture, whilst remaining sufficiently well drained to avoid oxygen deficiency due to waterlogging. A vineyard located on a slope tends to be better drained than those located on flat terrain.

Furthermore, grape quality is enhanced when the wine is slightly stressed through ‘adverse’ soil conditions, such as hard soil or water stress. However such adverse conditions will decrease yields.

Grapevines also prefer neutral soils that are neither acidic nor alkaline. Acidic soils can occur through an excessive use of chemical fertilisers and alkaline soils can occur in areas of low rainfall.

Vineyard Management

There are several different vineyard management systems available to the viticulturalists depending on their beliefs and also cost considerations.

a. Conventional Farming
– Mechanical harvesting.
– Use of chemical sprays.
– Large yields.
– Minimise human labour.
– Suitable for large flat vineyards.
– Produces cheaper wines.

b. Organic Farming
– Use of copper and sulfur sprays instead of toxic chemical sprays.
– Aims to improved soil health and structure through employing other natural farming methods such as natural compost and cover crops in between rows.
– Require more understanding of the vineyard and human inputs.
– Increased risk as copper and sulfur don’t protect the vineyard against extreme cases of disease.
– Copper and sulfur residue in the soil and wines can have a negative influence on soil health and winemaking.

c. Biodynamic Farming
– Builds on Organic theory by recognising the link between plant growth and the moon cycle and the latter’s influence on the sap within the vines.
– Uses natural biological preparations to enhance soil health through the promotion of beneficial bacteria and fungi in the soil rather than toxic chemical sprays.
– Improved grape quality through increased natural resistance to disease and healthier soils. It can also result in thicker skins, which increases colour, flavour and tannins in the wines.

d. Biologicial Farming
– The Biological approach to viticulture is based on measuring the microbial life in the soil and then applying the microbes, nutrients, compost tea, that the soil needs to regain its balance.
– An important part of this is an understanding of the Soil Succession Cycle. The fungal to bacterial ratio (F:B) is different in different types of ecosystems, so, the optimal F:B ratio is dependant on what is being grown.
– Using this knowledge means that composts, compost teas and soil additive programmes can be tailored to suit the specific land area and the desired crop or tree species.

Vine Cycle

1. Dormancy
The vine rests over winter, shedding its leaves and preserving the glucose in the roots and trunk.

2. Budburst
In early spring, green shoots and buds begin to grow.

3. Flowering
In late spring the vine flowers. This determines the number of grape bunches on the vine and therefore yield.

4. Post Setting to Veraison
After flowering, small berries set. At first they are small, green in colour, hard, astringent and high in acid.

5. Veraison
Veraison is when the grapes change colour and the skins become softer. There is a decrease in the proportion of acid as the sugar levels increase in the grape.

6. Harvest
When the grape has reached optimum maturity, it will be harvested. Harvest date is decided when the acids and sugars in the grape are balanced and also when the flavours are sufficiently complex and but not over ripe.


Back to Education