The time it takes to grow a mullet varies depending on the length you desire and your hair’s growth rate. On average, hair grows about half an inch per month, so a short mullet may take around 3-6 months to grow out, while a longer one could take up to a year or more. Factors like genetics, age, and hair care habits can influence hair growth speed. During this growth period, regular trims can help maintain the shape and prevent split ends.