Green Harvesting Grapes
What is green harvesting?
Green harvest is when winemakers prune the extra fruit from their vines. It's often done around veraison, a time when the grapes start to change from green to purple. This is an easy way to see the ripest grapes since they will turn purple first. The greener fruit will probably always be a little less ripe because of the way the plant is feeding that cluster of grapes.
There are other tricks wine makers know. Grapes closer to the base of the plant tend to receive more energy. Clusters usually get fed from the foliage above them so if a grape is near the base of a stem, it gets more energy. If the leaves above a grape cluster are damaged or dead, then that cluster will likely never fully ripen.
So green harvest is where you go through and harvest the green grapes. You can just throw them out, you can make compost, you can try to use the oils and fluids in the unripe grapes for other products, etc. The list of new applications for these green grapes is growing all the time.
Green Harvest SlideshowClick thumbnail to view full-size
Why green harvest?
A plant can only get so much sunlight and energy in a year. If it has to divide that energy between lots of fruit, the fruit will not get very ripe. If the plant has just a little bit of fruit, you'll get fewer, more delicious grapes.
There are ways to naturally limit the yields, but you might get a little unexpected surprise like extra rain in the springtime. And you end up with lots of fruit. So if you don't need a lot of quantity and you want more qualitative grapes with a lot of ripeness and flavor, you can green harvest to artificially lower the yield.
Another benefit is that a plant can get too crowded sometimes. There are two siginificant drawbacks to this crowding. On one hand, the density can hide leaves from the sun and suffocate the plant. There's no use having a bunch of leaves if half of them are receiving no sunlight.
On the other hand, too much crowding can make the grapes susceptible to bursting a little. This happens when the grapes push into each other too much or when the grapes expand because water cannot evaporate fast enough because of a lack of wind and sunlight. The bursting itself isn't so bad, but it makes them susceptible to diseases which can only take hold once the skin is damaged.
Green harvest allows you to make sure none of your grapes will get overcrowded so you can make the best wine possible on your vineyard.