Sounds like a good idea. I would be sure to freeze your rhubarb (to help
break down the fruit, because it is a pretty hard fruit) and thaw before you
make the wine. I've got rhubarb in the freezer right now; as soon as I get
enough I'm going to make some. You know, rhubarb blends well with other
wines, but it will yield to the other fruit. I have this one batch which is
still aging (I didn't have enough of each fruit to make a 1 gallon batch)
rhubarb, blueberry, & strawberry. You may also want to use precipitated
chalk to remove the oxalic acid taste, if you don't like the taste. When I
make rhubarb wine, I use oranges instead of lemons for the acid requirement,
but if you don't mind a little lemon aftertaste, then don't worry about it.
Rhubarb can make a pretty acidic wine and cherry sometimes comes out a
little low in acid. Should be a good combination but you might think about
making them separate and then blending them to taste. Just a thought. I
have 5 gal's of rhubarb I am holding back for blending now.