1. Fill a water-bath canner with enough water to cover eight half-pint canning jars by at least 1", then bring to a boil over high heat. Wash and rinse jars and keep hot until ready to use. Wash screw bands and lids and set aside.
2. In a large bowl, crush berries with a potato masher until mostly broken down, then transfer 5 cups to a large Dutch oven (reserve any extra for another use). In a small bowl, whisk 1/4 cup sugar and the pectin, then stir into berries.
3. Bring mixture to a boil over medium-high heat, stirring frequently to prevent scorching. When mixture has reached a rolling boil, stir in remaining 6 3/4 cups sugar until dissolved. Cook, stirring frequently, until mixture returns to a rolling boil, then boil for 1 minute and remove from heat.
4. Ladle hot jam into prepared jars, leaving 1/4" of headspace at the top. Wipe rims clean, then apply lids and bands and twist until bands are fingertip tight. Carefully add as many jars to canner as will fit in a single layer and cover with lid. Once water returns to a boil, process jars for 10 minutes, then turn off heat, remove lid, and let jars sit 5 minutes. Transfer jars to a wire rack and repeat with remaining jars.
5. Let jars sit 12 to 24 hours before checking for vacuum seals. Refrigerate any jars that aren't vacuum sealed and use within 2 weeks. Remove screw bands from sealed jars, then label and date; store in a cool, dark, and dry place for up to 1 year. Refrigerate jam after opening and use within 2 weeks.
Source: Hannaford fresh Magazine, September 2021