Strawberry Freezer Jam: Makes Five - 8 oz. Jars. 4 cups mashed strawberries, 1 1/2 cups sugar, 1 packet freezer jam pectin, 1. In a large bowl, crush strawberries until only small pieces remain and mixture is quite liquid. This may take a few minutes. 2. In a small bowl, mix Pectin and sugar together until incorporated. Add to mashed strawberries. Stir for 3 minutes. 3. Ladle into clean jam jars, leaving 1/2″ space at the top. Cap and let sit for 30 minutes. Store in your freezer.