Italy, France, California… all countries where ‘harvest’ is synonymous with ‘autumn’. Like ‘Christmas’ is synonymous with ‘winter’. Nevertheless, the Australians celebrate Santa in their thongs on the beach instead of going skiing. You got it: in the southern hemisphere the seasons are reversed and therefore, when here it’s winter, on the other side on the equator summer is reaching its height. This is how everything goes – including the harvest.
In honour of all the people who are rolling up their sleeves in the northern vineyards to pick up the fruits of the 2015 harvest, we want to take you on a journey to discover how we get to this great moment every year. Because to realize a wine tastes good is a matter of minutes – if not seconds – just the time we need to down a glass, but this is thanks to a much longer process, which takes place mainly in the vineyard and has more to do with the capacity of man to live harmoniously with nature than with his skills to adjust some faults in the cellar. We are talking about the vine cycle – and we want to tell you about this in an unusual way: upside down.
It all starts with a cry
The vine is one of the plants more related to the history of man and like children, who are born crying, vines wake up from their winter dormancy in the same way. When at a depth of 25 cm the ground temperature reaches 10°C again, sap comes out of the pruning wounds, the biological activity of the vine resumes and water and minerals flow again through its trunk and shoots. This happens in… September-October. Cause we are following the vine cycle in the southern hemisphere. From this moment on new shoots and leaves start to grow and will do so until about February, reaching their pick in December when flowers set. The highest hazard for the new buds is spring frost. In the early stages of its cycle, the vine needs a good supply of water and nutrients, but things will change.
By November-December the temperature reaches 15°C (20°C is even better) and flowering begins. Besides being a dazzling spectacle for the fortunate ones who can view it up close, this is the moment in which plenty of sunlight and a little water play in favour of a great vintage: heavy rainfalls would interfere with pollination. Each pollinated flower grows into a grape; this process is called ‘fruit set’. Depending on the grape variety and the seasonal conditions, around 25% of the flowers fail to fertilize and drop off; if the phenomenon reaches worrying proportions, it is referred to with the French term of coulure.
Towards January-February the grapes start to change colour: véraison is the sign the level of sugars inside the berries is growing to the detriment of the malic acid. The grapes are ripening, they swell gathering the water which was since then stored in the leaves and varietal flavours start to develop. The tannins ripen as well and the vine needs warmth, plenty of sunlight and a mild water stress in order to address the nutrients towards its fruits, rather than to its green parts. Summer pruning assures the leaves canopy is well open to favour the ripening of the grapes and prevent fungal diseases. Finally, shortly after véraison, green harvest takes place: it consists in cutting off the unripe bunches in order to control the final yield and share the resources available among a smaller amount of bunches – which will then be of higher quality.
The great moment
In the southern hemisphere, March-April is harvest time! Everybody hopes the weather is good, as excessive rain or hailstormes could cause the grapes to swell, diluting flavours, and/or ruin the crop by breaking the grapes skin and increasing the risk of rot. The right moment for harvesting the grapes is when they reach the ideal balance between sugar ripeness and physiological (tannins) ripeness, without forgetting the importance of retaining a good acidity which will make the wine more ‘alive’. This will vary depending on the grape variety and other factors. Also, in the hottest regions, the good weather speeds up the ripening process: the grapes could then be ready to be harvested from the chemical point of view, but would still need time to fully develop their spectrum of aromas and flavours.
After the labour of the harvest, vines too need to rest: between July and September the temperatures progressively go down, increasing the risk for frost. The shoots turn into permanent wood and the vines store their reserves of nutrients in their roots. They will need them to survive the winter and to fuel a new cycle in the spring until the new leaves will allow the photosynthesis to start again. In the regions with continental climate, in order to protect the vines from freezing, earth may be piled up to cover the graft union (most of the European vines are grafted onto an American’s vine rootstock following the Phylloxera crisis) and in extreme cases the whole vine is buried.
The Curiosity Corner
This summer has been really hot. Fortunately, the vines haven’t suffered too much: in most cases, there was sufficient water deep in the ground and the temperature range between day and night was wide enough not to put the vines under extreme water stress. But we’ve just said that a mild water stress is good for the quality of the grapes. Why?
As every other plant, if left to nature, vines focus their activity on simple reproduction: they would need to ripe their grapes just enough to attract birds so that they can spread their seeds. With plenty of water available, they would also tend to put their resources into growing the plant, rather than ripening fruit. The viticulturalist, on the other hand, needs riper grapes for winemaking. Pruning is performed to reduce the number of leaves and guarantee the bunches are well exposed to the sunlight and the air can circulate under the canopy. If the water availability is reduced, the vine feels ‘in danger’ and therefore addresses more resources to fruit ripening, rather then growing its green parts. This is why a mild water stress is good for the quality of the grapes – and of winemaking.
Photo Licence by Stefano Lubiana – Germogliamento