How long will a Purple Hair dye last?

I did this to make hair last summer and i really liked the results! The only down side is that it starts to fade after about two weeks. It depends though how much you wash your hair, so only wash it when necessary. The color will be there about the first two weeks, but then gradually start to fade and get less vibrant. I found purple color works the best. Go to a hair Salon and they'll usually have good color dye on hand