How Does a Winemaker Know When It's Time to Pick the Grapes?

​One of the most important decisions a winemaker makes happens before the grapes ever enter the winery:When do we pick?
It sounds like a simple question. You wait until the grapes are ripe and then you harvest them, right?
Not exactly.
Choosing the right moment to pick is a combination of science, experience, weather forecasting—and a whole lot of walking through the vineyard and tasting grapes.
It Starts With the NumbersAs grapes ripen, their chemistry changes. Sugar levels rise while acidity generally falls, so throughout the ripening period we collect samples and monitor what's happening inside the berries.
One measurement you may hear winemakers talk about is Brix, which gives us an indication of the sugar concentration in the grapes. Sugar is important because during fermentation, yeast converts that sugar into alcohol.
But Brix is only one piece of the puzzle.
We also look at acidity and pH. These measurements help us understand the overall balance of the fruit and give us clues about how the resulting wine may behave in the winery.
If we only picked according to a Brix number, though, we'd be missing a huge part of the story.
Then We TasteThis is where winemaking becomes much less about a laboratory and much more about experience.
We walk the vineyard and taste the berries.
And we don't just taste the juice.
We'll squeeze the grapes, examine the pulp, look at the color of the skins and inspect the seeds. We'll chew the skins and seeds to evaluate their flavors and tannins.
With red wine grapes especially, we're looking for something called phenolic maturity. We want the skins, seeds, flavors, color and tannins to develop alongside the sugar.
A grape can technically have enough sugar to make wine and still not taste ready.
That's why tasting matters so much.
The Seeds Can Tell Us a LotEarly in ripening, grape seeds tend to be greener and can taste very bitter or astringent when you chew them. As the grape matures, those seeds begin changing color and their flavors become less harsh.
The skins change too.
We want to see how easily color is being extracted and how the tannins feel in our mouths. We're also paying attention to the actual flavor of the berry. Depending on the varietal, we're looking for the disappearance of underripe or overly vegetal characteristics and the development of the fruit and flavor profile we want in the finished wine.
And Then There's the WeatherYou can have beautiful numbers and grapes that are almost exactly where you want them—and then look at the forecast and see several days of heavy rain headed your way.
Now you have a decision to make.
Do you pick a little earlier than you'd planned?
Or do you leave the fruit hanging and take the risk because you believe another few days on the vine will make a better wine?
This is where experience becomes incredibly important. Winemaking isn't simply following a formula. Every growing season presents a different set of conditions, and every decision involves balancing what is happening in the vineyard with the style of wine we're trying to make.
So, When Are Grapes Ready?When everything comes together.
We're looking at sugar. We're looking at pH and acidity. We're tasting the fruit. We're examining the skins and seeds. We're watching the weather. And we're thinking about the wine we eventually want to put into the bottle.
Sometimes the answer is obvious.
Other times, we walk the vineyard, taste the grapes, check the forecast, look at the numbers…and decide to give them just a little more time.
Because once you pick the grapes, you can't put them back on the vine.
And sometimes those last few days can make all the difference.

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