Here's a simple recipe that we created for using both blueberry (or any berries) and rhubarb. We use the Pumona's pectin (a low sugar pectin) so you can reduce the amount of sweetener and still get a perfect result. The jam tastes like pure blueberries even though it requires minimal amounts - the rhubarb blends well with the berries and helps to stretch the volume of jam you get. You can use fresh or frozen berries and rhubarb.
Wild Berry-Rhubarb Jam
4 cups chopped rhubarb (make sure you have some pink stalks so you get a richer colour of jam)
1/2 cup water
2-3 cups blueberries or other berries (mulberries, blackberries, service berries)
1 1/2 Tbsp lemon juice
4 cups sugar
2 tsp calcium water (this comes in powder form with the Pumona's pectin)
4 1/2 tsp Pumona's pectin
1. Bring rhubarb and water to a boil, and simmer 5 minutes or until thickened.
2. Add berries and sugar, and heat to dissolve sugar.
3. Blend with a submersible blender until jam has desired consistency.
4. Add calcium water and pectin as directed on Pumona's instructions.
5. Bring jam to a hard boil for at least 1 minute.
6. Ladle hot jam into hot, clean and sterilized mason jars.
7. Follow regular jam processing instructions (add hot lids and rings, process 5 minutes once canner returns to a rolling boil).
Makes 7 1/2-8 cups jam.