What are the signs that wine grapes are ready for harvest?

Question

I know that you are looking for about 22 to 26 degrees brix, but what are the other signs? How do you know they should have more "hang time" and when you should harvest?

Answer 1

Wine grapes need more sugar to produce a higher alcohol content when fermented. Grape growers like wine grapes to reach 20 - 24 percent sugar ideally. Grapes are variety dependent. Acidity is also important when considering the ripeness of wine grapes. Too high acidity will make the wine taste acidic and bitter and too low will make the wine flat.

If you are growing grapes to make wine, you might want to invest in an instrument called a refractometer to measure the sugar content of your grapes. This tool makes it easy to find out how much sugar is in one or more berries. The juice of the berries
is squeezed onto the refractometer plate, the plate is closed, and then by holding the instrument towards the light you can look into the eyepiece and see what the sugar reading is.

A less expensive means is to use a hygrometer. You need at least 50 berries to determine the sugar content by this method though. Hygrometers are more accurate than a refractometer and that's the trade-off. The hygrometer is floated in the
grape juice obtained by squeezing the berries and the sugar content is read off the scale in the neck of the hygrometer.

The pH of the juice is related to the acidity, it is more convenient for the small grower to use a portable "pH pen". A pH of between 3.00 and 3.55 generally indicates that the acidity of the grapes is in the for making wine.
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Answer 2

In damp climes, spraying with Bordeaux mixture begins midsummer. Some vineyards pull or remove leaves from around grape clusters to improve air circulation and reduce the possibility of bunch rot. Where weeds have been allowed to grow between the rows, they are plowed or hoed. Long shoots trimmed every two to three weeks to concentrate vine metabolism on the fruit.

About mid-Summer, comes veraison, the onset of ripening as the grapes begin to soften and swell significantly, while green varieties turn translucent and black grape varieties gain color. This signals the winemaker to prepare his equipment for the harvest. It is time also for diligent bird control in the vineyards.
Scarecrow on vineyard guard duty.

The grapes now begin to sweeten as sugar is transported from the leaves into the fruit. The berries swell from increased water content that dilutes the concentration of the acids. Flavor compounds and tannins also begin to build. Monitoring the grapes will soon move from weekly to daily, anticipating harvest, as vineyard managers test sugar levels and winemakers taste for maturity and ripeness...

Answer 3

when they taste right. That is how the Europeans do it. I took some from a vineyard in Alsace, & took them with me to Burgundy, in very early September. The lady of the hotel we stayed in tasted them & pronounced they were not ripe enough yet. They tasted okay to me, but the practiced pallet knows.
The sweeter the wine, the more rasin-like you let them get too. It concentrates the flavor.

Answer 4

tasting. The sugar content should be high but you don't want them to be on the verge of souring.