Put mulberries in a large clean jar and pour vodka on fruit until fruit is covered.
Cover jar tightly. Set in a cool, dark place for 1 month.
Strain the alcohol to remove all seeds, stems and fruit.
Pour strained mixture into a large glass jug or jar. Add the sugar and stir well.
Cover and store in a cool, dark place for 4 to 6 months, stirring everyday for the first 2 weeks.
After the 4 to 6 months are up, strain again into decorative bottles.