Remove all the grapes from the grape vines and discard of any grapes with blemishes or rotten spots.
Place grapes in your favorite fruit cleaner and let soak. I also like to blanch the grapes in boiling water for 30 seconds. I think it makes them juicier!
Wash the canning jars and lids in very hot soapy water or place jars in a large pot of boiling water. You’ll want your clean jars to be warmed up for the next step!
Fill your canner with water to the quart sized water bath line, or so that the jars will be submerged by at least an inch once they are in the canner.
Set it on the stove and heat water to a boil over medium-high heat.
Put the funnel in the jar and pour ¼ cup sugar into each quart.
Fill each jar to the top with grapes and then top the jar off with boiling or very hot water.
Leave ½-1 inch headspace at the top of the jar, wipe jar rims with a clean towel dipped in vinegar, add the lid and secure the screw bands finger tip tight. You don’t want to really crank them down, because air needs to be able to escape as it heats in the boiling water.
Use the jar lifter to transfer the grape jars to the water bath canner. Watch out for steam! It can really burn you. The jars should be close, but not touching. 7 quart jars give me full canner loads and fit perfectly in my canner, and I’m guessing they will fit in yours, too. Once the water has reached a full rolling boil, set a timer for 15 minutes. Once the jars are done processing, I shut off the burner and wait until the water stops spoiling before I remove the jars from the canner.
If I were canning a food like pickles that are prone to turning mushy, I would remove the jars immediately. But the grapes don’t mind! Set the jars on a few layers of tea towels and leave them undisturbed overnight. Let the hot juice cool slowly!
The lids have probably not sealed yet, and over the next few hours you will probably start hearing soft little “ping” sounds as they seal. Wait at least 12-24 hours before testing the seal and removing the rings. You need to make sure the jars of grape juice have came to room temperature. Give the glass jars a good shake once a day or so until they have a deep purple color. Label to jars and put them in your pantry for later!