Castor oil is another powerful oil for hair growth, thanks to its high ricinoleic acid content. This fatty acid has anti-inflammatory and antimicrobial properties that can help soothe the scalp and create a healthy environment for hair to thrive. Castor oil is also known to boost the production of keratin, the primary protein in hair. This makes it a favorite for those trying to grow out their edges or recover from hair thinning and breakage.