I found this on a cooking site's FAQ, I hope it helps! Paulette
Q: How do you freeze rhubarb?
Fresh rhubarb can be easily frozen to enjoy later on in the year, when rhubarb season is over. To freeze, simply wash and chop rhubarb stalks into recipe size pieces (e.g. 1/2 or 1 inch pieces). Pack rhubarb pieces in freezer bags or containers and place in the freezer. To use, just add the frozen rhubarb to your favorite recipe. You may need to increase the baking time slightly.