Thoroughly crush blueberries, one layer at a time. Stem and pit sour cherries and finely chop. Combine fruits and measure 3 1/2 cups into 6- to 8-quart saucepot. Measure sugar and set aside. Mix fruit pectin into fruit in saucepot. Place over high heat and stir until mixture comes to a full boil. Immediately add all sugar and stir. Bring to a full rolling boil and boil 1 minute, stirring constantly. Remove from Ladle quickly into hot jars, filling within 1/8-inch of tops. Wipe jar rims and threads. Cover with two-piece lids. Screw bands tightly. Invert jars for 5 minutes, then turn upright. After 1 hour, check seals. Or follow water bath method recommended by USDA.
This recipe yields 5 (1 cup) jars.
Yield: 5 cups