Prepare the Berries: Wash the aronia berries thoroughly, removing any stems or debris. If using frozen berries, allow them to thaw before use.
Mash the Berries: In a large pot, mash the aronia berries with a potato masher or use a blender to slightly blend them, leaving some texture for the jam.
Combine Ingredients: Add the mashed berries, sugar, lemon juice, and pectin to the pot. Stir well.
Cook the Jam: Place the pot over medium heat and stir constantly until the sugar has dissolved. Bring the mixture to a boil. Continue to boil for about 10-15 minutes, stirring frequently.
Test for Consistency: To test if the jam is ready, place a small spoonful on a cold plate. Let it cool for a minute, then run your finger through it. If it wrinkles, the jam is set. If it’s too runny, continue to cook for a few more minutes and test again.
Jar the Jam: Once the jam has reached the desired consistency, pour it into sterilized jars. Leave about 1/4 inch of space at the top of each jar.
Seal and Store: Seal the jars with lids. If you plan to store the jam for a long time, process the jars in a boiling water bath for 10 minutes. Let the jars cool completely before storing in a cool, dark place.