The best way for hair growth using amla is to apply the oil either overnight and wash it off or apply the oil for 15 to 30 minutes and wrap it with a moist warm towel and then wash your hair with a gentle shampoo.elow mentioned are the reasons. 1  It’s a known fact that massaging the scalp increases blood circulation but massaging the hair scalp with amla oil has many added benefits. 2  Not only does it help in blood circulation, amla oil is known to remove the unwanted flakes off the scalp.