In the last harvest series blog, I talked about sampling the vineyard to determine ripeness and picking date. In this blog, I discuss what happens during the actual harvesting of the grapes.
Once a picking date is decided upon, the vineyard manager will usually have to hire contracted labor to do the actual harvesting, if they don’t already have their own employees. In California, as in other states where produce crops are grown, you either have employed harvest workers or you have to hire contractors for the day. These workers will often be contracted to harvest up to three crops in a day, and they may be different fruits or vegetables in different parts of the state, too. Alternatively, a vineyard crew can use a mechanical harvester machine, which requires a lot less workers.
image from wine folly.
Grape harvest usually happens in the middle of the night or early morning when it’s cool outside. Crews using hand-held pruners work under spotlights, cutting off each cluster and filling small picking bins, which will in turn be emptied into larger bins. The nighttime harvest allows the grapes to stay cool, which allows the winemaker to be able to let the grapes “cold-soak” for 1-3 days before adding the yeast to start fermentation. Cold-soaking allows enzymes added by the winemaker to break down and release pigments, tannins, and sugars from the skins and pulp into the juice before fermentation. This adds depth to the final product. If grapes are too warm, spontaneous fermentation from the grapes’ own natural yeasts can easily start before the winemaker has a chance to introduce the specific yeasts they want to use (I will discuss yeasts in a later blog). A nighttime harvest also allows the winery crew enough time in the day to crush, destem, and press all the fruit before the day is over (although it is not uncommon to be processing into the night, too).
If a mechanical harvester is used, the machine can be driven over the vine rows, and berries are removed without harming the vines or the trellising systems. The harvester works by using vibrating rubber bars to shake the berries off of the stems. They are collected by conveyer and dumped into picking bins. Newer harvesters can even sort the grapes from the “MOG” (material other than grapes), which cuts down on the processing time at the winery. It takes 2-3 people to harvest using a mechanical harvester, and up to 100 tons can be harvested in a day, compared to 1-2 tons a day per person with human labor.
Once the harvesting is done, the grapes are weighed in 0.5-1 ton picking bins and taken to the winery’s crushpad for processing. The next harvest series blog will discuss destemming, sorting, and pressing white grapes.