With a trip to the winemaking store and the purchase of wine bottles, cork, cheesecloth and a nylon straining bag, you can be well on your way to your very own homemade wine. Although wine can be made from most kinds of grapes, it is the Vitis vinifera variety, from which Zinfandel and Merlot are made, that is perhaps the most famous. No matter which kind of grapes you have growing in your garden, the key to success is harvesting the grapes, which should be done in the late summer or early fall, after the grapes ripen.
Look for grapes that are round and plump. Rotting or shriveled grapes should be discarded, as should grapes with insects on them or insect damage.
Taste the grapes and learn when they are ripe for picking. They should be sweet with a little bit of tartness. To help you learn about your grapes and the art of harvesting them, squish three or four grapes in a cup and test the weight or gravity of the juice with a hydrometer, available at the winemaking store. The weight of the liquid determines how much sugar it contains. Good winemaking grapes should have a hydrometer reading of around 1.0982 specific gravity, or, depending on your hydrometer, should read 22 ounces per gallon, also called degrees Brix. This reading can be lower or higher depending on how sweet you want your wine to be.
Pick the grapes by hand in the morning, when it's cooler. Use a one-gallon bucket to drop the grapes in as you move from vine to vine. Pull the grapes right off the vine, but try not to get the stems, which you'll have to remove before making the wine.