A grapevine is an example of a perennial plant.
It grows or blooms over the spring and summer, dies back during the autumn and winter months, and then repeats the cycle from its rootstock the following spring. Without human intervention, grapevines will naturally grow into a bushy-tree-like mess of leaves and branches. Pruning and training help the vines stay nice and organized, and focus their energy on growing impeccable grapes.
The first year of growth in a vine’s life is meant to build up nutrient stores.
Any flower clusters that grow are usually cut back, so that the vine can focus its energy on establishing a strong root system. Producing fruit so early is to the vine’s detriment. Usually by the third year of growth, a vine is ready to produce fruit of proper quality for winemaking. Generally a grapevine matures over a period of up to 30 years, before slowing down dramatically in vigour. This is where the commercial term “old vines” may be applied by some wineries. During the first few years of a vine’s life, the growth of the permanent wood (trunk) and building a solid root system is the most important thing.
One of the most expensive and most important activities in the vineyard (besides harvest) is winter pruning. The previous year’s canes are cut back and the pruner chooses the best canes to grow new shoots for the coming year’s harvest.
DuringApril/May, or Sept/Oct in the Southern Hemisphere, the first signs of life occur, sap rises up and the buds begin to break. The buds are extremely delicate during this time, for spring hailstorms can destroy them. For example, in Beaujolais, France during the 2016 vintage, some vineyards lost 100% of their buds because of hail.
After the buds break in early spring, they continue to grow. Some viticulturists prune the downward facing shoots to ensure that all the shoots grow upward and to reduce the potential crop size. This strategy involves reducing quantity to increase quality because vines that produce limited numbers of grapes produce more concentrated grapes.
The flowers of grapevines are called perfect flowers: they pollinate themselves without needing bees.
In June and July, Nov/Dec in the Southern hemisphere, young clusters begin to appear. These clusters will eventually become berry bunches.
In mid to late summer, the green berries start to change colour and ripen. This time period is called vérasion (“verre-ray-shun”) and it’s the most beautiful time of the year in a vineyard when the berries change colours from a vegetal green to yellow, pink, red or purple. Just before vérasion begins, some wine growers do green harvesting, wherein a little excess weight is removed from the vines (the superficial grape bunches) so that the vines can focus their energy on the remaing grapes.
The wood continues to ripen over the course of the summer, turning brown and hardening. In tandem with wood growth, the grapes continue to ripen and the sugar levels rise. Harvest usually occurs some time between Sept-Nov, (February – May in the Southern Hemisphere) when the grapes are in the proverbial “sweet spot.” Harvest time is a crucial moment when the grapes reach their perfect ripeness. Viticulturists and harvesters work around the clock to pick the grapes in time. Grapes do not continue to ripen once picked.
In the late Autumn, some producers leave a few bunches on the vine for a late-harvest wine. The grapes raisinate (dry out) and are later pressed to make a very sweet, dessert wine. At this point, the vine has stopped producing carbohydrates from the chlorophyll in the leaves. The leaves then lose their colour and fall to the ground.
From November, (May in the Southern Hemisphere), winter returns, foliage dies off, vines are trimmed and pruned, and the cycle begins once again.