When the concord grapes get ripe, we like to make jam! Here’s how we do it.
You’ll need two quarts of concord grapes, six cups of sugar, two small saucepans, a strainer, a canning pot and accessories, and three pint jars with lids and bands.
Wash the grapes and measure out two quarts. In this picture, there are enough for three batches (six quarts).
Next, peel the grapes, putting grapes in one pot and peels in another. When the grapes are ripe, you can just give them a squeeze and the grapes pop right out of their skins.
Cook the grapes without water and the peels with just a little water in separate pots for ten or fifteen minutes until the peels are soft and the grapes are separated from the seeds.
Combine the peels in a larger pot with sugar (3 cups per quart of grapes). Strain out the seeds from the pulp, and add the pulp to the sugar mixture. Bring to a boil until jam reaches the gelling point. You can test this with a candy thermometer (211° in Denver), a spoon or by putting a plate in the freezer.
Ladle your hot jam into hot jars. Process pints in a boiling water bath for 15 minutes here in Denver. Process five minutes less if at sea-level or using half-pint jars.
Voilà – Grape jam!
The Lazy Homesteader 
Our grape jam didn’t set right– it’s yummy, but the wrong consistency, which I’ve heard is due to a lack of pectin from the peels. What’s your take on that?
It could be? We cook the peels about 15 minutes before combining them with everything, and then boil it all together, and have never used added pectin with the grapes. I know if you have a few under-ripes ones, they have more pectin.
I’ve gotten more careful about checking for the gelling point (and sometimes making it a bit stiffer) after our cherry jam turned out to be cherry syrup this year. Also, Noelle Taylor, from the Monroe farm told me that if you make jam on a humid or rainy day, it won’t ever gel right. She mentioned it on facebook and got a bunch of people saying they had the same experience. So maybe it was too humid outside??
Annie – check this out – the last page talks about re-processing: http://www.uga.edu/nchfp/publications/usda/GUIDE%207%20Home%20Can.pdf
and this: http://healthworks-lifeworks.com/strawberry-jam-failure-how-to-fix-it/
Also, Dave was telling me about Pamona’s pectin. I noticed they had some at Berry Patch, and he said he got his at Vitamin Cottage. I guess you mix a little with water and just use what you need. Might be a good way to correct your jam if there wasn’t enough natural pectin in the grapes??