As is often said, a vine as it grows older produces less quantity of grapes but of a better quality as they are more concentrated. There is a point however where the old vines need to be replaced by new. Economics dictates this moment but is affected by a number of factors. There is no rule but this ocurrs between 50 years and 100 years, depending on how well the vines were pruned and treated, the soil, the grape variety (Merlot lasts longer than Cabernet).
Normally a wine producer would replace the old vines that happen to die within a vineyard plot ‘racotter‘.
When is the best time to plant young vines? It is best to do this in November as there is no need to water the young plants (the first year is the only time one is allowed to water within the appellation contrôlé or AOP as it will be called from 2013 Appellation Origine Protegé – but that is another story!) but obviously this is a busy time in terms of vinification. Planting young vines in November is not possible in areas prone to frost.
Otherwise planting is best done in April. Sometimes a whole plot is uprooted when there many ‘manquants’ around 30%. These young vines are bought from the ‘pépinieriste‘ and are already grafted onto american rootstocks (porte greffe).
The winemaker chooses the rootstock that suits his ‘terroir‘ and its adaptability to the moisture particularly in the soil. It is an important decision as it dictates the quality of his wine for 60 odd years. Each little plant cost around 1.10 euro so it is an large investment each year in terms of product and labour.
In addition you need to add the costs of the plastic sleeve (to protect the plant from herbicide spraying only for when you plant young next to old ‘racottage’), the fertiliser, water and the pole ‘marquant‘ (the small vine is planted to the east or north of this pole as they don’t like the sun).
The two main rootstocks used in St Emilion for example is the 101-14 for moist zones and the 3309 for drier soils. They produce a similar quality of grape. A baby vine that is planted in amongst older vines needs to be able to withstand vigorous competition.
It is the European vitis vinifera which is grafted by the ‘pépinieriste’ onto these rootstocks. There are different strains of the different grape varieties such as Merlot for example with different potential yields and therefore quality.
When do vines come into production? The little plants have wax around their grafts to protect them from the cold. The baby vines come into production in the third year (photo above shows two year old plants). They are the first to be harvested as they ripen first and represent a very good concentration of fruit up to seven years. Little by little they produce more and more fruit. Often the fruit from the young vines goes into the second wine until it reaches adulthood at around 15 years of age.
The process of replanting should be a continual one so there is a good balance between old and young vines in the vats.
Today a young vine can produce better quality than a vine of 60 years of age. S04 was planted in the past and the focus was producing quantity not quality. Today the rootstocks used produce limited quantity and better quality (concentration) of grapes. It is possible to visually recognise S04 as there is a swelling of the vine exterior to the soil (will try and take a photo to illustrate). No-one in St Emilion for example buys S04 anymore.