Pick Concorde Grapes When Ripe

Q. We had a nice sized crop of Concord grapes this past summer. The grapes were still a bit small compared to what I’m used to. They are more sweet than tart but I’m not sure how much longer to leave them on the vine. Any thoughts?

A. Grapes no longer develop sugar once they are picked. Other examples of fruit that don't ripen after picking are cherries and figs. Leave them on the vine as long as you can.

This is what Concorde grape should look like

Some fruits like peaches and plums continue to develop sugars and become sweeter after they have been harvested. When you pick grapes, figs and cherries, what you pick is what you get.

Bunches of grapes as well as the berries themselves ripen at different times. Usually a good time to harvest is when there is a small percentage of the berries that are overripe and beginning to shrivel.

Concord grape grown in the desert doesn't seem to develop the same color or sweetness that it does in New England.

Don't harvest grapes all at once. Harvest bunches which are ripe and delay harvesting those that are not quite ready. You may harvest 2 to 3 times a week depending on how hot it is.

The hotter it is, the faster they ripen. As grapes ripen, sugar content increases about 1% every 2 to 3 days. The best indicator is to taste them. If they taste good, they are ready to harvest.

Next year, remove smaller bunches so that remaining bunches are spaced about every 10 to 12 inches apart. Cut about one third off of the bottom of the remaining bunches. Do this when the berries are about the size of a small pea.

As long as the vines are getting plenty of water during fruit development and their thinned, you will get larger berries and bunches.
Just a note. Concord grape is a New England grape and will not perform the same in the hot desert climates.