Blackberry Jam
The ratio needed to make jam is 3 parts crushed blackberries or strained pulp to 2 parts sugar.
For jam with seeds:
9 cups (6 or 3 cups) crushed berries
6 cups (4 or 2 cups) sugar
squeeze fresh lemon juice
Wash and pick over blackberries, crush, place in large pot. Add sugar, lemon juice and boil for 15-20 minutes (or temp reaches 220 degrees). Pour into jars and seal.
For seedless jam:
4 lb (2 lb) blackberries
2 lb (1 lb) sugar
squeeze fresh lemon juice
Wash and pick over blackberries, heat until soft, and pass through a sieve to remove seeds. The juice that remains will be the amount you need for the 3:2 ratio with the sugar.
Add sugar and lemon juice and boil for 15-20 minutes or until temp reaches 220 degrees. Pour into jars and seal.
Click here for instructions on how to prepare jars for canning and sealing.