Instructions:
- Prepare the Blackberries:
- Rinse the blackberries under cold water to clean them, and remove any stems or leaves.
- Lightly mash the berries with a fork or potato masher, leaving some chunks for texture.
- Sterilize Jars:
- Sterilize your canning jars and lids by boiling them in water for 10 minutes. Keep the jars hot until ready to use.
- Cook the Jam:
- In a large saucepan, combine the mashed blackberries, lemon juice, and sugar.
- If you’re using fruit pectin for a firmer jam, stir it in now.
- Bring the mixture to a rolling boil over medium-high heat, stirring frequently.
- Once it reaches a boil, cook for 1-2 minutes, stirring constantly. Skim off any foam that forms on top.
- Test the Jam:
- To check if the jam has set, place a small spoonful on a cold plate and let it sit for a minute.
- If it wrinkles when you run your finger through it, the jam is ready. If not, boil for another minute and test again.
- Fill the Jars:
- Carefully ladle the hot jam into the sterilized jars, leaving about 1/4 inch of headspace.
- Wipe the rims with a damp cloth to remove any residue.
- Seal the Jars:
- Place the sterilized lids on the jars and screw on the bands until fingertip-tight.
- Process the jars in a boiling water bath for 10 minutes.
- Cool and Store:
- Remove the jars from the water bath and let them cool completely on a towel or cooling rack.
- Check the seals by pressing down in the center of each lid—it should not pop back.
- Store sealed jars in a cool, dark place for up to one year.