This page provides an Overview of Robertson Valley wine production.
Climate
In South Africa, viticulture mainly takes place at a latitude of 34° south in an area with a mild Mediterranean climate. The Western Cape is cooler than its position might suggest, with conditions that are ideal for a wide range of noble vine varieties. The traditional winegrowing areas along the coastal zone are seldom more than 50 kilometers from the ocean and experience beneficial breezes blowing in from the sea. The temperate climate features warm summers and cool winters with frost rarely a problem. Rain falls mainly between May and August. Further east and towards the north, the Klein Karoo, Olifants River and Orange River areas tend to be warmer and drier.
With its ancient soils, South Africa is considered to be the cradle of mankind. The impressive Cape mountain ranges form a dramatic backdrop to one of the most beautiful wine producing areas of the world. The vineyards lie on the valley sides and floors, benefiting from the many different meso-climates offered by the mountainous terrain and diverse terroir. There's constant interaction between the rugged peaks and multi-directional valley slopes and the proximity of to two mighty oceans - in particular the Atlantic, chilled by the icy Benguela current which flows northwards up the west coast of Africa from the Antarctica - moderates the summer warmth. Cooling breezes blow in from the sea during the day, fog and moisture-laden breezes are prevalent at night. Adequate sunshine plays an important role too. This diversity of topography and meso-climatic conditions results in wines of character and complexity.
The Cape floral kingdom is the smallest but richest of the world's six floral kingdoms which creates a unique biodiversity. In the Cape winelands, grapes grown in one single block can show variety. The grape quality has been positively affected by better matching of varieties to locations in recent years. Extensive research and practical experience have been combined to establish which micro-climates suit particular grape varieties in order to find the ideal conditions for the wide selection of varieties that South Africa has adopted from every corner of the wine-producing world.
Prospect1870 Private Estate is situated in the Robertson Valley
Dubbed the 'valley of vines and roses', the Robertson district's lime-rich soils make it eminently suitable for racehorse stud farming and also, of course, for good wine. The construction of a major dam at the beginning of the century brought reliable and inexpensive irrigation and this led to the proliferation of Robertson's many wine estates and co-operatives.
Situated in the Breede River Valley region, the average annual rainfall is around 400 mm. Although summer temperatures can be high, cooling south-east winds from the coast - less than 100km away - channel moisture-laden air into the valley. Today, Robertson is renowned for the quality of its wines and while traditionally considered white wine territory and known for its Chardonnays, it is also the source of some of the Cape's most revered Shiraz, while the distinctive fortified dessert wines for which it was originally famed continue to be produced. The district of Robertson incorporates several wards.
Robertson and Breede River Valley Soils
The Breede River is generally bordered by Silurian sandstone mountains and ridges. The northern reaches of the valley (Tulbagh; Fig. 3) are underlain by Malmesbury Group greywacke and mudstones (Visser, 1984), often covered by Quaternary boulder beds. The middle and lower reaches of the valley (Worcester, Robertson) are generally underlain by Devonian Bokkeveld Group shales (350-395 Ma), as well as Permian Dwyka tillites and Ecca shales (250-340 Ma). Isolated areas of unconsolidated, Jurassic Enon conglomerate (180 Ma) also occur (Visser, 1984). Soils utilised for viticulture range from alluvium along river banks, to reddish-brown, often calcareous soils on older terraces, with higher lying weathered shale increasingly being exploited.
Aan de Doorns, Overhex, Nuy, Robertson, Ashton and Bonnievale, in a lower rainfall area and therefore dependent on water from the Breede River and Brandvleidam. This area features three main soil types: dark-coloured, light-textured, humid alluvial soils on the lower riverine terraces which induce vigorous growth; reddish-brown, heavy textured soils, often calcareous, on older, higher terraces which, depending on the salt content and structure, also promote vigorous growth of vines and high yields; relatively shallow red soils on Bokkeveld shale which induce moderate vigour of the vine and its yield if properly prepared. Colombard fares well here, as do muscat dessert wines.
Viticultural Practices
Viticulture involves practices such as soil preparation and tilling, growing and planting of varieties, trellising and pruning of vines, and combating disease.
Along with the type of variety chosen, soil, climate and winemaking techniques, these vital practices are the main factors which determine the quality and character of a wine.
When a vineyard is established, it is important that a thorough study is made of the
soil and climatic conditions to ensure that the most suitable cultivation methods are chosen. Thorough soil preparation is essential to create an environment for plant roots in which air and moisture are kept in the right proportion to solid material, and to ensure that there is sufficient nutrition to promote the best growth and production.
The choice of variety will depend on the composition of the soil, the climate, where the vineyard is situated and what kind of wine is desired. Varieties bearing heavier harvests are generally planted in areas under irrigation. In cooler regions, and where the soil is not very fertile, varieties which grow less densely are planted, as well as those that produce smaller but higher quality harvests.
Previously it was generally accepted that the higher the yield, the lower the quality of wine and vice versa. Research has shown this approach is not quite correct. Of great importance is the balance between leaves, which function effectively because of good exposure to sunlight and the quantity of grapes harvested. When there are not enough functioning leaves to sustain a large crop, the quality will be lower. Vines are climbing plants and are suitable for trellising. Stronger growing plants are usually trellised and can carry heavier harvests. As bunches hang higher off the ground, there is less chance of rot as a result of damp. The decision whether to trellis at all, and the type of trellising system used, is determined by the soil potential, variety, climate, growth and vigour of the vines. In areas where frost damage is prevalent trellising is required, while dry land vineyards with a weaker growth are often not trellised.
Seasonal Cultivation
As vines are deciduous plants and their growth follows the seasons, cultivation practices are equally dictated by the season. Spring (September to November)
In spring the nodes on the shoots begin to swell and bud. Soon they develop new shoots with leaves, eyes, runners and small flower clusters. By the end of October the vineyards bloom and pollination takes place. The soil is ploughed and fertilised, excess shoots are removed and shoots growing out of rootstocks are broken off just below the surface. Water is essential and in very hot, dry areas judicious irrigation is necessary. In damp conditions the vineyard is more susceptible to fungal disease and it should be treated accordingly, as well as against insects.
Summer (December to February)
As the weather becomes warmer, the grapes ripen. Growth control by topping and irrigation are now applied to ensure maximum ripeness. Preparations for the harvest are begun in the cellar and, when the grapes are ripe, they are harvested and pressed.
Autumn (March to May)
When harvesting is complete, the vine gathers reserve stocks of nutrients for the winter and wood grows hard to enable the shoots to resist winter cold. The leaves colour and fall, and growth ends. Fertilisation is again necessary and in areas where irrigation is used, the vineyards are thoroughly sprayed to encourage development of reserves. Disease control is important: as soon as the leaves have fallen, all the shoots except the bearers are removed by clean pruning.
Winter (June to August)
Winter is the resting period of the vine and no visible growth takes place. After good rains have fallen, the vines are heavily pruned and the soil fertilised where necessary by ploughing crops and natural weeds into it.
