Jamie Goode: Is there a more important winemaking decision than picking date?

One of the critical decisions facing winegrowers is when to pick. But what is optimal ripeness? Assuming that this question can be answered, it still leaves uneven ripeness levels in the same vineyard block as a confounder: if there’s variation in the vineyard or even within the same grapes on a vine, it makes choosing picking date really tricky even if you know what ripeness level you are aiming at.

No vineyard is uniform. There will almost always be differences in soils across a farm, and where a vineyard isn’t flat, there will be differences from top to bottom of the slope. There might be shade from trees, and the last vine in a row will typically be a bit more vigorous because it has less competition. And the orientation of the row might change the ripeness of bunches on each side of the vine, particularly if the orientation is north-south, because the side exposed to the afternoon sun is usually hotter. Another level of variation could be differences in the way the vines are pruned, or disease or pest pressure. Some vines might have a poor graft union, or be affected by viruses, or have some trunk disease. Or they might have generated some mutations in the actively dividing bud primordia after sitting outside in the sun for thirty years, and thus differ from their neighbours (this is the basis of clonal variation). All these factors contribute to variations in ripeness within the same vineyard.

Precision viticulture approaches look to identify within-vineyard variation that can then either target portions of the vineyard for differential harvest, or for tailored management to reduce that variation. But this variation is real and can make harvest decisions tricky. Also, within each bunch of grapes there will be some variation in ripeness levels in the grapes. It’s most obvious at veraison in red varieties, when some berries become coloured while others remain green. This can be an issue, and it’s very hard to manage. Viticultural expert Alain Deloire has shown me data of the ripeness levels of berries in the same bunch at harvest, and there always seem to be substantial differences, so some variation is inevitable. The question is, how much variation is too much?

What happens during ripening? Berry development begins with flowering, and each berry is the result of pollen arriving on the style of the female part of the flower and germinating, sending a pollen tube that grows and finds its way to the ovule, where fertilization takes place. If fertilization of flowers in a cluster is asynchronous, then we have the beginning of ripeness variation in the bunch. This is compounded by the position of berries within the bunch.

Having said all this, if this sort of variation is managed well, then it makes choosing a picking date easier. While variations in ripeness can be good for white wines – and some winemakers appreciate the differences between bunches on the east and west sides of vines when the vines are planted north-south for their white varieties – it isn’t desirable for reds. This is because when macerations are involved, the skins need to have a certain amount of ripeness or they might contribute undesirable green flavours and tannins that are experienced as too-astringent or bitter.

After veraison, ripening begins in earnest. Acid levels (mainly malic acid) begin to decline, sugar accumulates, skins soften, and the tannins begin to change their form, becoming less bitter and astringent. Flavour molecules accumulate in the skins. As the berry ripens, the seed coat colour changes from green to brown: this is the result of oxidation of compounds in the coat, not lignification. Lignification is what happens to the stems, which also change from green to brown.

In the wine world we are currently seeing a change of opinion about what constitutes appropriate ripeness for red wines. In classical wine regions where ripening took place in autumn, waiting as long as possible and then picking before autumn rains was a good strategy, because it resulted in wines with not only nice flavours, but also plenty of them. Winegrowers frequently lost their nerve and picked early, and the wines were often tight and tasted a bit unripe. The best sites were those that ripened fastest and, in general, more ripeness was better because it was pretty hard to reach a state of over-ripeness. So sugar accumulation was a good guide for when to pick. In regions where chaptalization of must was common, getting to 13% potential alcohol was a victory, and if you could get to 14% it was a miracle.

But over recent decades most regions have got warmer, and viticulture has got better too. Warmer temperatures and bigger, healthier canopies, coupled with lower yields for ambitious wines has led to riper and riper wines. The consultants helped winegrowers start off in the direction of riper wines with sweeter fruit, but they didn’t advise their clients that just because some extra ripeness is good, that more than a bit isn’t necessarily desirable. And when these consultants travelled to warmer regions where attaining full flavour ripeness has never been a problem, their advice that had been appropriate for cool regions wasn’t so helpful.

Now the problem for many of the world’s wine regions is deciding when to harvest, because there is no perfect intersection between flavour ripeness and sugar ripeness. In an ideal world, you would pick when the sugar ripeness is giving you a potential alcohol level of 12-14%, and a pH of 3.1-3.4 (this can be lower for sparkling wines and varieties such as Riesling, and at the higher end for reds – remember that the pH at harvest is different from the pH of a finished wine when malolactic fermentation takes place). For reds, you don’t really want a pH of higher than 3.7 in the finished wine, although in some regions this regularly gets close to pH 4 and the wines seem fine. The reason for avoiding higher pH is microbial stability. Yet in many regions you won’t get both of these occurring together, and it’s common for winemakers in warmer regions to wait for flavour ripeness and then live with higher alcohol levels and correct the pH by tartaric acid additions.

This is where we get to debate the notion of flavour ripeness. Simply put, I think too many winegrowers pick too late, especially for red wines. They are looking for the wrong flavours. Yes, some consumers enjoy ripe, sweet, jammy red wines, but these usually require new oak to replace the missing structure and acid additions that stick out in the final wine. The big problem is that these are wines of style: they have lost any nuance of place, and have just become modern, international red wines that could have come from anywhere. It’s understandable why people are tempted to pick later, but I rarely speak to a winemaker who says that they missed the pick by going in too early.

Of course, it is possible to pick to early and produce a wine of style rather than a wine of place. But few seem to do this. In California, the In Pursuit of Balance organization that was active for a few years brought together winegrowers looking to make wines that were more balanced than some of the Californian wines that were getting big critic scores. The wines from the member wineries showed clearly that this was the future for California, and resulted a pendulum swing back to better balanced wines. Yes, some still pick too late, water back, and add acid, but this is now no longer the trend.

For whites, picking late hasn’t been such an issue, but there is certainly a move to picking earlier and getting brighter, fresher wines.

But there’s a caveat here. To be a good winegrower, you have to read your place. Some places don’t have a talent for making tight, acid-driven wines with low alcohol, and forcing this style on them will result in rather hollow wines. While the importance of flavour ripeness has been exaggerated in the past, it is still a real thing. And a point well made by Eben Sadie is that if you are to pick early, you need to adapt your farming to make early picking feasible.

In conclusion, I’d say that picking date is a foundation of making good wines. It’s absolutely critical, but it isn’t the only critical decision.

• Jamie Goode is a London-based wine writer, lecturer, wine judge and book author. With a PhD in plant biology, he worked as a science editor, before starting wineanorak.com, one of the world’s most popular wine websites.