Combine the berries, cherries, sugar and lemon juice in a large, heavy-duty saucepan. Mix well and let sit for 10 minutes. Bring to a boil over medium-high heat. Continue to boil, stirring frequently, for 10-15 minutes, or until mixture thickens into a jelly-like consistency.
Remove from heat and immediately pour into mason jars. Seal tightly and let cool. Store in the refrigerator for 4-6 weeks or the freezer for 6 months.