Yes, rosemary oil can be beneficial for low porosity hair. Low porosity hair has tightly closed cuticles, which can make it difficult for moisture and other beneficial ingredients to penetrate the hair shaft. Rosemary oil has been found to have a stimulating effect on the scalp, promoting blood circulation and potentially aiding in the absorption of nutrients. It also has antimicrobial properties that can help maintain a healthy scalp. Additionally, rosemary oil is known to have moisturizing and conditioning properties, which can help hydrate and soften low porosity hair.