Applying red onion juice to the scalp might help hair growth and hair regrow. It improves blood circulation and provides the hair follicles with sufficient nourishment. Onion also has anti-bacterial properties, so it helps with scalp infections that might contribute to hair loss. Red onions have silicones that help in the growth of hair follicles from the roots. Onions contain high sulfur content which is important for the formation of a key structural component of the hair called keratin. How often to use: you can apply this remedy once or twice a week. It can take 3 to 4 months to produce any visible results.