4 cups fresh or frozen blueberries
2-1/2 cups fresh or frozen red raspberries
2-1/2 cups fresh or frozen strawberries
1/4 cup lemon juice
2 (1 3/4-ounce) packages powdered pectin
11 cups sugar
Combine the berries and lemon juice in a large kettle; crush fruit slightly. Stir in pectin. Bring to a full rolling boil over high heat, stirring constantly. Stir in sugar; return to a full rolling boil. Boil 1 minute, stirring constantly. Remove from the heat; skim off any foam. Pour hot mixture into hot jars, leaving 1/4-in. headspace. Adjust caps. Process for 15 minutes in a boiling-water bath.