To grow thick eyebrows naturally: 1. Castor oil This is an old and one of the most effective remedies for getting thicker eyebrows. Make sure that you apply castor oil every day on your eyebrow roots, it promotes hair growth and also ensures that each hair strand is thick and strong. Method: Massage a few drops of castor oil into your eyebrows with your fingertips. Then brush it .Keep it on for 30 minutes, wipe it . Egg yolk- Twice weekly , after applying castor oil beat an yolk till it is smoot