4 C. watermelon, remove seeds (not rind) 3 1/2 C. granulated sugar 2 T. lemon juice 1 (6 oz.) bottle liquid fruit pectin
Place watermelon in blender or food processor and blend or process until smooth. You should end up with 2 cups purée.
In large cooking pot combine watermelon purée, sugar and lemon juice. Bring mixture to a full rolling boil. Add pectin all at once. Boil hard for 1 minute, stirring constantly. Remove from heat; skim off foam.
Ladle jelly into clean hot half-pint jars; seal. Process in a boiling water bath for 5 minutes. Makes 4 half-pints.