Cornrow Maintenance Make sure that your cornrows are not braided too tight. Cornrows that are too tight can pull the hair out from the roots, mostly around the edges. Cornrows cannot be washed. Trying to wash your hair while it’s corn rowed will make your cornrows unravel quickly. Your cornrows should last 2 to 4 weeks. Using a silk scarf, tie your hair every night, and if it starts to get frizzy use a bit of gel before tying the scarf.