Make the Jam

• Rinse the blackberries and add them to a heavy-bottomed pot. Gently mash to your desired consistency.
• Stir in the sugar and lemon juice.
• Place the pot over medium-high heat and bring to a rolling boil, stirring frequently.
• If using pectin, add according to package instructions.
• Continue boiling for 10–15 minutes, stirring often, until the jam thickens and coats the back of spoon.

Test for Doneness

• Place a small plate in the freezer ahead of time. Spoon a bit of jam onto the cold plate and return it to the freezer for about a minute.
• Push the jam gently with your finger. If it wrinkles, it’s ready.
• Alternatively, use a thermometer and cook until the jam reaches 220°F.

For Refrigerator or Freezer Storage

• Let the jam cool slightly, then transfer to clean jars.
• Leave 1/4 inch headspace for the refrigerator or 1/2 inch for the freezer.
• Refrigerate for up to 3 weeks or freeze for up to 1 year.

For Canning

• Prepare jars by washing and keeping them warm.
• Fill hot jars with hot jam, leaving ¼ inch headspace.
• Remove air bubbles and wipe rims clean.
• Apply lids and rings until fingertip tight.
• Process in a boiling water bath or steam canner for 10 minutes (adjust for altitude).
• Remove and let cool undisturbed for 12–24 hours. Check seals before storing.