Harvest 2026: How Do We Know When Grapes Are Ready to Pick?

Harvest 2026 has begun at Château Latour-Monplaisir. But the decision to pick the first grapes is made long before they reach the winery.

As harvest approaches, berries are regularly sampled from different vineyard plots, then analysed, observed and tasted. Because a grape can look ripe, contain enough sugar, and yet still need more time to reach the level of maturity we are looking for.

Choosing the right harvest date is therefore a matter of balance, bringing together scientific measurements, sensory analysis, knowledge of the vineyard and experience.

What happens inside a grape as it ripens?

Ripening is a complex process that gradually transforms the composition of the berry.

From véraison, when red grapes begin to change colour, sugars produced through photosynthesis accumulate in the berries. At the same time, acidity evolves: malic acid in particular decreases as the grapes ripen, while tartaric acid remains comparatively more stable.

For the future wine, the balance between sugar and acidity is essential. Sugars will be converted into alcohol during fermentation, while acidity will contribute to freshness, balance and the overall profile of the wine.

But other, less immediately visible changes are taking place at the same time. Phenolic compounds found particularly in the skins and seeds are evolving too. These include anthocyanins, which are largely responsible for the colour of red grapes, and tannins, which will contribute to the wine’s structure and ageing potential.

And importantly, all these elements do not necessarily mature at the same pace.

Measuring sugar ripeness

One of the tools we use as harvest approaches is the refractometer.

Its principle is based on the refraction of light. Just a few drops of grape juice are needed: the instrument measures how light bends as it passes through the juice, providing an estimate of its concentration in soluble solids, which at this stage consist predominantly of sugars.

This allows us to monitor sugar accumulation and estimate the potential alcohol level of the future wine.

During our checks ahead of the 2026 harvest, measurements showed that the grapes were approaching the sugar levels we were looking for. In this respect, they were close to what is known as technological maturity.

But that did not necessarily mean they were ready to pick.

Technological maturity vs phenolic ripeness

This distinction is particularly important when deciding when to harvest.

Technological maturity is generally assessed through the evolution and balance of sugars and acidity. Phenolic ripeness, on the other hand, concerns the development of the berry’s phenolic compounds and, particularly in red grapes, those found in the skins and seeds.

Why does this matter?

The tannins extracted during winemaking will play an important role in the structure and texture of the finished wine. When grapes are not sufficiently ripe, these tannins can be more astringent and accompanied by distinctly green or vegetal characters. As the berries mature, both the nature of these tannins and the way they can be extracted evolve.

To produce wines that combine structure, generosity and the ability to age, we are therefore looking for more than a sufficient concentration of sugar. We are looking for balance throughout the berry.

What can grape seeds tell us?

Tasting begins with observation.

When we open a berry, one of the elements we look at is the seeds. As the grape matures, these gradually change in appearance. Green tones give way to shades of brown as the seeds mature and lignify.

Colour provides a useful indication, but it is never considered in isolation.

We also taste the seeds. When they are still immature, their flavour can be distinctly green and herbaceous, with pronounced astringency. As they mature, these vegetal characters begin to fade and drier, more developed flavours emerge, sometimes reminiscent of almond.

The grape skin is also observed and tasted. Its texture and resistance, its aromas and the sensation of its tannins provide further information about the development of the berry.

This is where the experience of the winemaker complements analytical measurements.

When the numbers say “soon” but the grape says “not yet”

This is precisely what we observed at Château Latour-Monplaisir in the days leading up to the 2026 harvest.

The refractometer showed that sugar concentration was already approaching the level we were looking for. Yet when we opened and tasted the berries, the seeds still displayed a noticeably herbaceous character. The first almond-like notes were beginning to emerge, but they were not yet sufficiently developed.

Sugar ripeness and phenolic ripeness were simply not progressing at exactly the same pace.

So we decided to wait.

At this stage, we returned to the vineyard every three days to taste and observe the berries, closely monitoring their development and waiting for the different indicators to move towards the balance we were seeking.

Why not simply wait longer?

It might seem logical to assume that the riper the grape, the better the wine. In reality, the decision is far more nuanced.

While phenolic ripeness continues to develop, sugars may continue to accumulate and acidity may continue to change. Waiting too long can lead to higher potential alcohol levels, reduced freshness or an aromatic profile that no longer corresponds to the style of wine we want to produce.

There are external factors to consider too: temperature, rainfall, the health of the grapes and the weather forecast can all influence the decision.

Choosing a harvest date is therefore always an arbitration between several factors. The objective is not to reach a theoretical point of perfect ripeness, but to identify the moment when the grapes offer the best possible balance for the wine we want to make.

Harvest 2026: from vineyard to winery

After weeks of monitoring and months of work in the vineyard, Harvest 2026 is now underway at Château Latour-Monplaisir.

The grapes are leaving the vineyard and arriving at the winery, where another series of transformations begins. Sorting, fermentation, extraction and, later, ageing will gradually reveal the character of this new vintage.

It is still far too early to say what 2026 will become. That uncertainty is part of what makes this moment of the year so fascinating.

Analyses provide us with numbers. Tasting gives us another set of clues. Experience allows us to interpret them.

And somewhere between the three lies one of the first defining decisions of a new vintage: knowing when to pick.