3 pts. blueberries - okay to use frozen blueberries, do not thaw, thoroughly
2 tbsp. lemon juice
7 c. sugar
2 pouches Certo pectin

Crush the blueberries (in small amounts) in a blender or with a masher. Measure 4 1/2 cups crushed blueberries into a large 6 to 8 quart pot. Add lemon juice. Stir sugar into blueberries. Mix thoroughly. (Add 1/2 teaspoon butter to reduce foaming). Bring mixture to full rolling boil over high heat, stirring constantly.

Open Certo pectin pouches and quickly stir into blueberry mixture. Bring to full rolling boil, stirring constantly. Continue boiling for 1 minute, stirring constantly. Skim off any foam with large metal spoon.

Fill all jars immediately to 1/8 inch of tops. Wipe jar rims and threads. Cover quickly with lids. Screw bands tightly. Invert jars for 5 minutes then turn upright. After 1 hour, check seals.