Swenson Red grapes makes good jelly. Not as good as Concord Seeded. I guess that figures, if Concord is the standard that grape jellies are judged by.
Last year because the robins were feasting on my trellis ( I have an arbor also) grapes big time, I harvested the grapes before they were fully ripe and the jelly was not as tasty as the two prior years that I had made jelly from Swenson Red grapes. Sort of reminds me of going into Caesar’s Wine and Liquors store and asking the clerk why the huge jugs of wine was much cheaper than the 750 ml bottles of wine. Of course, the answer was that the grapes used for making the wine in the huge bottles was much inferior to the grapes used for the wine in the standard bottles. Maybe the birds were after the grapes that used for in the wine in the huge bottles as in my case. Who knows?
I use Ball Low or No-sugar pectin while using 2 cups of sugar per batch
of 8 half pint jelly jars following the Ball recipe.
Not familiar with Red Currant.