Delicious homemade jam made with fresh picked blackberries!
Prepare lids and jars.
In a stockpot, crush 10 cups of blackberries over medium heat using a potato masher.
Press the crushed fruit through a small mesh strainer or cheese cloth to remove seeds.
Measure 6 1/2 cups of sugar into a separate bowl.
Measure 5 cups of crushed blackberries into a large saucepan.
Stir in Sure-Jell pectin into fruit. Stir in butter (this reduces foaming).
Bring mix to a rolling boil on high heat. Stir constantly.
Add sugar to fruit mixture. Bring back to a rolling boil. Boil for 1 minute.
Remove from heat. Remove any foam.
Ladle right away into your prepared jars. Fill them within a 1/2 inch to the top. Cover with lids.
Place jars into boiling water. Be sure to cover jars by 1-2 inches. Add more boiling water if needed. Cover. Boil for 10 minutes.
Remove the jars and place on a towel to cool. When cooled, press the center of the jars. If they spring back to you then you will need to refrigerate your jam since it did not process properly.
Let stand for 24 hours and then store in a cool, dry place.