Whether you have a few grapevines in your backyard or a large vineyard, knowing when and how to harvest the fruit is critical to success and avoiding crop failure.
Grapes don't ripen any further after being harvested so you want to make sure to pick them when they're mature - not too early, and not too late. In general, and depnding on the type and/or variety, grapes mature on the vine from late August to late October.
Here's some tips for recognizing when grapes are mature and ready to be harvested from the vine. In general, you might want to pick several grapes from different clusters located on the upper and lower parts of the vine, and from shaded and unshaded areas. Doing so gives you a more representative measurement of ripeness than if you pick grapes from just one bunch.
- Color - First, examine the grapes' color. As they ripen, and depending on the variety (cultivar), grapes have a rich color, changing from green to near-blue purple, deep red or crisp white.
- Feel - Feel the shape of a grape and squeeze it between your thumb and forefinger. Ripe grapes lose a bit of firmness when they ripen, and pop with juice when squeezed. Unripe grapes usually shrivel softly and dribble juice when squeezed.
- Taste - Each variety of grape has what's known as a "varietal flavor." You want to wait to pick them until they have the right flavor. Only way to do this is by picking a few grapes and eating them.
After determining that the grapes are mature and ready to be harvested, then you can pick them. Vineyards use machinery or pick by hand but, if you're a backyard gardener, chances are you'll be picking grapes by hand.
How to harvest grapes
When a cluster of grapes is mature and ready to be harvested, grab the cluster and support it with your hand. You don't want it to fall to the ground as this may bruise the grapes. Using a sharp pair of hand pruners or picking shears, cut the cluster from the vine leaving about one-half the length of stem attached to the cluster.
As you harvest, gently place each cluster in a harvesting container or basket. Dropping the grapes into the container can cause them to bruise.
More details for harvesting grapes for wine...
The most important day of the year is the day you pick. It sets in motion the annual harvest and it also determines the kind of wine you'll make. As a grape grower and a wine maker you should keep a notebook. You'll be glad to have records in the months and years to come.
Brix Testing - Brix is a term that the brewing industry uses to measure the sugar content of grapes. Brix level helps estimate the alcohol level of your wine. Like temperature, Brix is measured in degrees. Brix is measured with a refractometer, which you can buy at a winemaking supply store or online. Drop some juice on the test plate, close the cover firmly and look through the viewfinder. You'll see a line where your juice registers on an internal Brix scale. Grapes for white wine should measure between 20 and 22.5 degrees Brix; grapes for red wine should measure between 22.5 and 24.5 degrees Brix. Keep an eye on our grapes, testing them periodically, and when we reach our Brix goal, then it's time to pick.
Testing pH - Squeeze several grapes in a cup to measure the pH of their juice. Use a digital pH meter if you are harvesting for wine making purposes. The pH of a grape decreases as its sugar content increases. A white wine grape should have a pH between 3.2 and 3.4; the pH of a red wine grape should measure between 3.3 and 3.5.
Keep records every harvest season that will help you in seasons to come!
Happy grape harvesting!
