Grape Harvesting 101 by Diane Sidebottom.
Whether you have a few grapevines in your backyard or acres of grape-producing vines, knowing when and how to harvest the grapes is critical to success. Make sure your grapes are ripe before you harvest. Grapes generally mature from late August to late November depending on the variety. Keep an eye on the color changes of the grape such as green to blue or red to white. Most cultivars color up long before they flavor up. Although color change is important, it is not the only consideration. When fully ripe, the natural bloom or whitish coating on the berries should become more noticeable, the seeds change from green to brown, and the berry becomes slightly less firm to the touch.
So, now we have covered the visual cues for ripeness, the best judge of when to harvest your grapes, taste them! Grapes will not continue to ripen after they are removed from the vine, and the longer they are on the vine, the sweeter they become. Grapes don’t require direct sunlight on the fruit to ripen and develop good color. Rather, the amount of light that reaches the plant’s leaves governs the quality of the fruit. The leaves manufacture the sugars that are then translocated to the fruit.
While maturing you will need to protect your ripening crop from critters, after all there is nothing like munching on sweet juicy grapes on a hot summer day. There are several methods you can use to achieve this goal. Netting the vines deters birds, as well as aluminum pie plates hung to twirl in the wind. You can place artificial owls, hawks, and snakes around your vineyard, but I personally don’t recommend the artificial snake, since your husband might think it’s funny to put it into one of your drawers for you to find. Human, dog and coyote scent helps to deter the deer, but it’s hard to get those coyote to stay where you want them.
So, the grape gods have smiled favorably and you actually have something to show from all your hard work. You have properly pruned the vines and cleaned up the grape leaves the previous fall, thereby helping decrease the number of overwintering pests. You have planted coriander or borage to help attract bees. You have planted chives and nasturtiums to discourage Aphids. You have planted Geraniums in and around your vineyard to deter Japanese Beetles. The Rose Chafer Beetles and the Grape Berry Moths are vacationing in California this year so no problems there. You have received enough rain to produce sufficient foliage but not too much rain and humidity to cause Powdery Mildew, Downy Mildew, or Black Rot. And if all else fails you pull out the insecticides and anti fungal and spray like a crazy person.
You, my friend, are ready to harvest. Make sure you have decent weather and grab your sun screen, hat and long sleeve shirt because after all, it’s summer in Texas. Get a pair of pruners that are sharpened, oiled and fit your hand. Grasp the cluster of grapes with your free hand and gently pull the cluster away from the vine while clipping it off with the shears. Leave a little bit of stem on the cluster for easy handling. Place the grape clusters gently in a container and keep them out of direct sunlight. Don’t stack too many grape clusters on top of one another, so you don’t damage the grapes. Continue harvesting.
After harvesting, you can store the grapes, possibly up to eight weeks, depending on the cultivar and storage conditions. Ideally, grapes should be stored at 32F with 85% humidity. If you have an abundance, grapes are excellent for making jellies, jams, juice and most notably, wine. If you intend to make wine, or if you just like gadgets, you may want to purchase a refractometer to determine the sugar content. A refractometer is a hand held device that measures the index of refraction of liquids. A juice sample is placed on the prism, and the device measures how the light is reflected, which corresponds directly to the sugar content of the sample. Wine grapes usually need a sugar content of 22 to 24% or more.
Remember, no matter how well you grow and care for your grape vines, your result can depend on the care and attention given to the harvest. So the next time you look at that $$ bottle of wine, reconsider the complexity of growing and harvesting grapes, and maybe it won’t seem so expensive.
As always, happy harvesting.