Clean your jars and lids with hot soapy water. Rinse clean.
Rinse berries and remove any stems or leaves.
Zest lemon to get 1 Tbsp (15mL) lemon zest.
Pulse blueberries in a food processor 3 times or until crushed to measure 2 cups (500mL), stopping to scrape down sides.
Place raspberries in a large glass bowl. Mash with a potato masher until crushed.
Add blueberries, sugar, lemon zest, and lemon juice to the crushed raspberries. Stir well.
Let the mixture stand for 15 minutes.
Gradually stir in pectin. Stir the mixture for 3 minutes.
Let the mixture stand for 30 minutes.
Spoon mixture into jars, leaving 1/2 inch (1 cm) headspace. Center the lid on the jars. Apply the rings and adjust them loosely.
Place jars in the freezer. Once the jam is frozen, adjust the bands to fingertip-tight.
Store in the freezer up to 1 year.
Thaw in the refrigerator. Refrigerate the jam after thawing, and use within 3 weeks.
Notes
This recipe will make about 5 (1/2 pint) jars of jam. The recipe is from the All New Ball Book of Canning and Preserving on page 308.You can use dehydrated lemon peel and bottled lemon juice for this recipe.