Growing update, and Harvesting

All of the rain this year, has ensured that the water table is high in the ground, and combined with a week of hot temperatures, the vines are showing explosive growth.

Too much so. The vines are pushing out growth shoots all over the place. I spent at least 3 hours this weekend pulling suckers, or unwanted growth shoots.

Professional growers typically try to harvest all their grapes from a given vineyard in the same day. A couple of few tests are used in conjunction to determine when to harvest the grapes.

First is taking a sampling of individual grapes from various spots in the vineyard and just tasting them. It is up the individual doing the tasting to decide what they are looking for in terms of flavor. Next is picking say a dozen individual grapes from random spots in the vineyard, then squeezing the juice into a container, mixing up the juice, then testing it for sugar level (Brix), and the acidity of the juice. It is very important that there is an important balance between the sugar level, and the acidity. Typically when the sugar level in the grape is low, the acid level is high. As the grape ripens and the grapes add more sugar the acidity begins to drop.

This balance can change rapidly. At some point as well, a grape vine will stop directing energy to the grape cluster, and in essence shut off the nutrient supply. The stem connecting the cluster to the vine will turn brown, and at this point the valve is turned off.

Water is nuetral between acidity and akalinity. PH is how acid/akalinity levels are measured. Water is a PH of 7.0, and this is considered nuetral. Acidity is important in wine making, because it contributes to crispness of flavor, it helps solidify the structure of the wine, and the right level of acidity prevents bacteria growth. Grape growers monitor the acid level of the grapes and look for a PH in the range of 3.3 - 3.5 when trying to decide when to harvest.

Acid levels are tested using a series of chemicals in certain proportions to measure the Acidity. Much in the same way Swimming Pool water is tested for PH levels.

Every grape varietal ripens a bti differently. Some ripen early in the season, and others require much more sunlight or degree days.

Sugar. In order to provide a minimum structure/stability to a wine, it needs about 12% alcohol. A Brix (sugar) level of about 22 - 23 will produce 12+% alcohol.
Brix/sugar levels can be tested with a refractometer. It's a small handheld tool.
Basically you take a drop of fresh juice squeezed from a grape, onto a glass prism. A plastic flap then covers the drop of juice. You then look an eyepiece and examine the sunlight that flows through the grape juice covering your prism. The unit has a small scale that shows how the Brix level of the juice based upon how if filters the light. It is a relatively simple exercise.

The dilemna is that every vineyard ripens inconsistently. Grape clusters at the end of a row of grapes will ripen more quickly than clusters in the middle of a row. Even all the clusters on a single vine will ripen at different rates. As such a professional grape grower, when the choosing a time to harvest, will have some combination of perfectly ripe grapes, overripe grapes, and underripe grapes. They pick a time to harvest and then they clear the whole field. This is typically done very early in the morning. Once any fruit is harvested, a natural by product is to produce more sugar. Buying green banana's as an example then a few days later, they are sweeter and softer. Plus heat accelerates this sugar conversion, so the grapes are harvested when it's cool ideally.

I don't harvest all at once. I only harvest what is ripe. The last few years I have harvested by vineyard in thirds. I have learned which area of my vineyard ripens first, then I harvest just that area. Maybe a week later another portion of my vineyard is ready, and I harvest that next. Lastly, it still may be a few days later, or another week or two, then I'll harvest my last section of my vineyard.

This means I have to ferment each batch at different times, and believe it or not, each batch of grapes will produce it's own unique flavor and characteristics.

More to follow on this.