Veraison – What was that again?

If you Google the French term “véraison” the English equivalent is “veraison.” Under the French entry it says, “Maturation des fruit, spécialement du raisin qui prend sa couleur.” That roughly means ripening of fruits, especially of the grape which takes its color. When I come across a term like veraison I always try to understand how the word was derived, essentially the etymology of the word. Now you have to admit that veraison is not your everyday term. I don’t know of any context the word is used other than in grape growing so I want to consider this term so that when you see it again the word will have stuck. The only difference between the English and the French term is the spelling. The French having an é, they mean the same thing; namely, veraison is the time when grapes change color and this change of color marks the beginning of the process of ripening that is a turning point in the life cycle of the vine – the onset of ripening.

Lifecycle of the Vine

In May bud break was followed the emergence of flower buds, inflorescence followed by the process of efflorescence, or the flowering of the vines. The period of efflorescence is when the flowers self-pollinate. Another crucial point in the lifecycle of the vine that occurs in late May and early June, the period we call fruit set. After fruit set from early June to late July, the green berries gradually increase in size with very little change in metabolism. In late July and early August the grapes start to change color marking a major change in grape berry development. Veraison marks the beginning of the ripening of the grape berries when the little green berries turn black in a black grapes, such as Merlot, and turn yellow in a white grape, such as Viognier.

For the ladies who read my blog, you could compare these lifecycle changes to a human pregnancy. Flowering to fruit set would be the first trimester, fruit set to veraison would be the second, and veraison would be the beginning of the third trimester. All the baby has to do now is get bigger and riper – or in the human condition bigger and stronger.

A Closer Look at Veraison

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Now how the plant decides when to change color is anybody’s guess. One of the safest bets to make when trying to understand plant physiology is to say it all depends on the amount of warmth and thereby the amount of sunlight a plant gets.

In trying to get to the bottom of the metabolic changes at veraison I looked it up in Wine Science by Ronald Jackson 3rd edition and I quote:

“A major shift in metabolism occurs simultaneously with veraison. That these changes are controlled by plant-growth regulators is beyond doubt. Regrettably, the specific actions of individual growth regulators remains unclear.”

Wine Science, 3rd Edition, by Ronald Jackson

At least I tried.

Veraison takes two to three weeks to complete and is most easily tracked in black grapes. In some grape varieties the change occurs more quickly than others and in some varieties like Cabernet Franc the berries change color at different times in the same bunch.

At the start of veraison the chlorophyll – green pigment on the black grapes – turns to anthocyanin that will develop the major components that make up the color of a red wine and are the building blocks for the tannins development. Sugars are transposed from the leaves and roots to the berries and as sugar and water accumulate so the acid levels in the grapes decrease.

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There are many more things happening in vine and in the grape berry than just the accumulation of water and sugar and the loss of acid. Remember that all of the magic aromas and flavors in wine ranging from Alvarino to Zinfandel come from the skin of the grapes, and many of those complex components develop from the beginning of veraison until harvest. Just like what controls the onset of veraison, just how the infinitely complex development of tannin and flavor components is beyond the reach of Science.

So there we have it, yet another inflection point in the never ending life cycle of the vine, and what’s more to the point, the amount of sunshine we have had in the last couple of weeks could not have been better.  Wine grape growers are weird, they are the only agriculturalists who pray for drought and by golly we’ve got it.

Thanks for reading,

Andrew Hodson