A Year in the Life of a Grape Vine

The yearly cycle of the vine is divided into nine different stages: We are looking at the growing cycle in the Northern Hemisphere.  Depending on the grape variety, each of the stages can take different lengths of time but the growth cycle will always remain the same.

1.  Renewal – The vines “wake up” as the sap rises to the cuts that are made during the winter pruning.

1. Budburst – At the end of March and beginning of April the dormant buds swell and split.  This produces new vine shoots which sprout between the Petiole (leaf stem) and the stem of the vine.  The number of buds which are produced is dependent on how many buds were left when the vine was pruned during the winter. If there is an unexpected frost during the budburst, it can be fatal or greatly affect the future harvest.

1. Leaf Growth – towards the end of spring the new shoots develop into leaves that unfurl and take on the shape that is distinctive to their grape variety.

1. Flowering – In June (or six to eight weeks following the bud burst depending on weather conditions), the milder temperatures and increased sunshine cause the flowers to emerge – the clusters (highest shoots blooming first)contain hundreds of small white flowers and this period lasts for approximately one to three weeks.  The flowers grow opposite the leaf and a good shoot will produce three or four clusters of flowers but the amount of flowers produced is dependent on the growing conditions from the previous season when the dormant bud developed.

1. Fruit Set – As June draws to an end, the pollinated flowers are transformed into small green balls that contain from 1 for 4 pips (seeds) each.  The weather conditions are critical during the fruit set. If it is too cold or damp, there is an increased risk of the flowers not being pollinated as the sap has not reached the flower, causing it to fall off without being pollinated. This can also occur if the plant does not have adequate fertilization.  Winemakers call this occurrence by the French word Coulure which translated into English means “shatter”.. Each pollinated flower forms a grape, if flowers are lost then the cluster of grapes will have missing grapes.  An  improperly formed flower results in the production of a tiny seedless grape in French which is called Millerandage. The presence of Milledrange causes future harvest to be either partially or completely destroyed depending on how severe the weather is. Once the flowers have turned into baby grapes, the winemaker is able to make an estimation of harvest yield.

1. Berry Growth – The hard green berries metamorphose during three stages. The first stage is the rapid growth phase where after fertilization, the seeds and berries develop into a firm fruit and are a dark green color.  The second stage (the lag phase) is a time of slow growth where the berries retain their firmness but begin to lose chlorophyll and undergo a rapid increase in acidity.  Towards the end of this stage, the grapes change color as they enter the Veraison Phase. White grapes turn from translucent to a golden color and red grapes transform from red to a deep blue. The third stage of the berry growth – Veraison is when the berry begins to reach maturity, there is an acceleration in growth as the berries start to soften and ripen. There is a decrease in Titratable Acid TA) as well as an increase in pH and soluble solids (Brix).  Berries often ripen unevenly within the clusters.

1. Ripening – The grapes grow and ripen over the summer, this is also a very critical period in the growing cycle.  Weather conditions will either positively or adversely  affect the maturation speed of the grape as well as  the acidity and sugar levels and aromas that develop. As the grapes start to ripen, the winemaker will regularly visit the vineyard to assess the quality of grapes and decide when to set the harvest date.

1. Harvest – After a long growing season that has been carefully monitored by the Viticulturist, the Winemaker has carefully monitored the ripening process and finally  has determined that the grapes are ready for harvest (this is the point when the sugars and remaining acids are well-balanced enough to be made into wine). However, the winemaker can choose to harvest the grapes when they are not completely ripe (for example Pinot Noir grapes that are used for sparkling wine as they have lower sugar levels then when they are fully ripe) or overripe (Botytris or Noble Rot) for sweet dessert wines.  The time of harvest depends on the style of wine that is being made.  Usually harvest is carried out through the month of September and into the month of October.  However, with the recent extreme weather, some vineyards began their harvest as early as the end of July in 2022!

1. Dormancy – once the grape harvest is over the vines go into a period of dormancy. This is the period when the vine has no growth activity which lasts until the bud burst the following spring.  How the vines are cared for during the winter period is crucial to ensure the success of the next year’s vintage.The time between the harvest and the first frost is a very critical time for the vines and there are many tasks that need to be completed during during dormant period  when though the vines appear to be asleep, there is a lot of microscopic activity happening and the vines and roots are active beneath their bark. Composting and/ or planting a cover crop to protect the vine roots against erosion and also ensures that the vines are fertilized early enough in the dormant season to ensure healthy growth during the next season.  Pruning and inspection of the individual health of each vine (checking for diseases such as wood fungus Eutypa – which is caused by excess water on the fresh pruning cuts) takes place between December and March.  The pruning process is dependent on the particular climate of a vineyard. Pruning is also important as it ensures the consistency in grape production and allows proper management of the vineyard. There is a different style of pruning for each vine which depends on the grape variety and the vigneron will select one or more buds to keep for the coming year.  The pruning process will determine the following year’s harvest even before the vine comes out of dormancy.  Depending on the size of the vineyards, the pruning process can take a few weeks or a few months.  Disease, harsh weather, damage by animals and old age can cause dead or severely damaged vines that need to be identified and removed and replanted in early spring after the last hard freeze to ensure the continuity of the vineyard.  New vines only produce grapes after three years, therefore the overall production of the vineyard is affected.  The viticulturist earmarks the plants that need to be removed when they are found throughout the year.

The yearly life cycle of the vine must be carefully managed by the viticulturist and winemaker.  The secret to a successful harvest and resulting wines produced by the property is the constant attention required through taking excellent care of the vines throughout the year.

Sante!