Rosemary oil or castor oil? Which one boosts hair growth more?

Breaking down the benefits, science, and best uses for each oil

If you’ve spent any time looking into natural hair growth remedies, you’ve probably come across hair oils. Specifically, rosemary oil and castor oil both have strong reputations for promoting longer, healthier hair—but they work in very different ways.

The real dilemma is choosing between rosemary and castor oil for the best hair growth boost. Better yet, the answer depends on your hair type, scalp condition, and what you’re hoping to achieve. Rosemary oil is known for stimulating the scalp and encouraging new growth, while castor oil is deeply moisturizing and helps strengthen strands.

The key to choosing the right oil? Understanding how they work and what your hair actually needs. Whether you’re dealing with thinning, dryness, or breakage, one of these oils—or even a combination—might be the boost your routine is missing.

 

What does science say about hair growth?

Before breaking down how castor oil and rosemary oil help hair, it helps to understand how hair growth actually works.

Hair grows in cycles, and factors like genetics, scalp health, and overall lifestyle play major roles in how fast and strong your strands grow. The scalp needs proper blood circulation, hydration, and nutrients to support hair follicles through the growth cycle.

 

How can oils impact hair growth?

Plant-based oils, including castor and rosemary oil for hair growth, can support healthy hair in a few key ways:

– Moisturizing the scalp: A dry, irritated scalp can lead to flakiness and weakened hair follicles. Oils provide hydration and help maintain a balanced environment for hair to thrive.

– Strengthening the hair shaft: Oils rich in fatty acids, like castor oil, coat the hair strand and protect against breakage, leading to longer, stronger hair over time.

– Encouraging scalp circulation: Rosemary oil is known for increasing blood flow to the scalp, which helps nourish follicles and potentially stimulates new growth.

– Reducing inflammation: Scalp inflammation can lead to hair shedding. Many oils have anti-inflammatory properties that soothe irritation and promote a healthier scalp.

– Protecting against damage: Regular oiling helps shield hair from heat, pollution, and styling stress, preventing premature thinning and breakage.

But while oils can be powerful tools in your hair care routine, they’re just one piece of the puzzle.

Other factors that affect hair growth

Even the best oils can’t override the deeper factors that influence hair growth. If you’re struggling with thinning or slow-growing hair, consider these key influences:

– Genetics: Hair growth rate, thickness, and texture are largely determined by your genes. While oils can optimize hair health, they won’t change your natural hair pattern.

– Diet and nutrition: Hair is made of protein, so a diet lacking in essential nutrients like biotin, iron, and omega-3s can slow growth and lead to excessive shedding.

– Stress levels: High stress can trigger hair loss conditions like telogen effluvium, where follicles prematurely shift into the shedding phase. Scalp massage with oils can help, but managing stress through lifestyle changes is key.

– Hormones: Imbalances in hormones—such as those caused by pregnancy, menopause, or conditions like PCOS—can affect hair thickness and regrowth.

– Scalp health: A clogged, irritated, or inflamed scalp can restrict hair growth. Proper cleansing and using scalp-friendly oils can create an ideal environment for hair to flourish.

– Hair care habits: Overwashing, excessive heat styling, and chemical treatments can weaken hair over time. Using oils as a protective barrier can help, but minimizing damage is just as important.

 

How does castor oil help hair growth?

1. Deeply moisturizing and strengthening

Castor oil is a thick, nutrient-dense oil packed with fatty acids—especially ricinoleic acid. This helps:

– Seal moisture into the hair shaft: Its heavy consistency coats each strand, reducing water loss and preventing dryness.

– Prevent breakage and split ends: Hydrated hair is less likely to become brittle and snap.

– Strengthen strands over time: Regular use can help fortify hair, making it more resilient against styling and environmental stress.

If your hair tends to be dry, coarse, or brittle, castor oil can help lock in hydration and reduce damage, making it particularly beneficial for curly, coily, and high-porosity hair types that struggle to retain moisture.

2. Improves scalp health

A healthy scalp is essential for strong hair growth, and castor oil offers several benefits:

– Antimicrobial properties: It has natural antibacterial and antifungal qualities, which may help reduce scalp irritation, itchiness, and dandruff.

– Anti-inflammatory effects: Ricinoleic acid can calm inflammation, making it a good option for people with sensitive or easily irritated scalps.

– Protective barrier: Because it’s so thick, castor oil creates a physical seal over the scalp, reducing moisture loss and helping to maintain hydration.

3. May promote hair growth

While castor oil doesn’t directly stimulate hair follicles the way rosemary oil does, its ability to improve scalp health and reduce breakage indirectly supports longer, stronger hair. When hair is well-hydrated and less prone to damage, it has a better chance of reaching longer lengths.

Some people also swear by castor oil for encouraging thicker brows and lashes. Though scientific evidence is limited, its moisturizing properties and ability to condition hair can make a noticeable difference in overall hair health.

What hair types is it best for? 

–  Dry, damaged, or brittle hair.

– Those looking to prevent breakage and strengthen strands.

–  Sealing in moisture, especially for curly and coily hair types.

 

Where does castor oil come from?

Castor oil is derived from the seeds of the castor plant (Ricinus communis), a hardy, fast-growing shrub native to tropical regions of Africa and Asia. The oil is extracted by cold-pressing these seeds, producing a thick, nutrient-rich liquid packed with fatty acids, particularly ricinoleic acid—a compound believed to have anti-inflammatory and moisturizing benefits.

Historically, castor oil has been used in medicine and beauty treatments for centuries. Ancient Egyptians were among the first to recognize its benefits, using it to protect and condition their hair in the arid desert climate. Today, it remains a staple in natural hair care for its ability to nourish the scalp, strengthen hair strands, and minimize breakage.

How does rosemary oil help hair growth?

1. Stimulates blood circulation

One of the key reasons rosemary oil is praised for hair growth is its ability to increase blood flow to the scalp. Healthy circulation ensures that hair follicles receive the nutrients and oxygen they need to thrive.

– Encourages follicle activity: More blood flow means hair follicles stay active longer, potentially extending the growth phase of the hair cycle.

– Supports thicker, fuller hair: By nourishing the scalp, rosemary oil can help strands grow in stronger and denser over time.

– Comparable to minoxidil: A 2015 study found that rosemary oil performed similarly to minoxidil (a pharmaceutical hair loss treatment) in promoting hair regrowth over six months, but with fewer side effects like itching and dryness.

2. Helps reduce shedding

If you’re experiencing increased hair shedding, rosemary oil may help slow down excessive loss by reducing inflammation and strengthening follicles. It’s packed with antioxidants that combat free radical damage, which can contribute to hair weakening and premature shedding.

– Soothes inflammation – Scalp inflammation can lead to hair thinning, and rosemary oil’s anti-inflammatory properties help create an optimal environment for hair retention.

– May prevent DHT buildup – Dihydrotestosterone (DHT) is a hormone linked to hair loss, particularly in androgenetic alopecia (pattern baldness). Some research suggests that rosemary oil may help block DHT from binding to hair follicles, preventing miniaturization and thinning.

3. Supports scalp health

A balanced, healthy scalp is essential for strong hair growth, and rosemary oil offers multiple benefits to improve overall scalp conditions:

– Antimicrobial properties: Helps combat scalp issues like dandruff, itchiness, and mild infections that could hinder hair growth.

– Regulates oil production: Whether your scalp is too dry or too oily, rosemary oil can help balance sebum production, ensuring a healthier hair environment.

– Encourages cellular turnover: Gently exfoliates and refreshes the scalp, preventing clogged follicles that could restrict growth.

What hair types is it best for? 

– Those experiencing hair thinning or shedding.

– People looking for a natural way to stimulate new growth.

– Keeping the scalp healthy and balanced.

 

Where does rosemary oil come from?

Rosemary oil is extracted from the leaves of the Rosmarinus officinalis plant, an evergreen herb native to the Mediterranean region. Known for its distinct herbal aroma, rosemary has been used for centuries in medicine, cooking, and beauty rituals. The essential oil is typically obtained through steam distillation, which captures its potent bioactive compounds, including carnosic acid, rosmarinic acid, and cineole—all of which contribute to its hair-boosting benefits.

Historically, rosemary was revered by ancient civilizations. The Greeks and Romans associated it with memory and vitality, while traditional Ayurvedic and Chinese medicine practitioners used it to promote circulation and overall scalp health. Today, rosemary oil has gained popularity as a natural alternative to conventional hair growth treatments, with some studies suggesting it may be just as effective as minoxidil, a common hair regrowth medication.

 

How to use castor and rosemary oil for hair growth

Both oils can be powerful additions to your hair routine—but they need to be used the right way.

Using castor oil for hair growth

Because castor oil is thick, a little goes a long way. Here’s how to apply it effectively.

1. Scalp massage: Warm a small amount of castor oil and massage it into your scalp to promote absorption.

2. Mix with a lighter oil: Blend it with a lighter oil like jojoba or argan to make it easier to apply.

3. Use as a pre-shampoo treatment: Apply it to the scalp and strands 30 minutes before washing to deeply hydrate hair.

Using rosemary oil for hair growth

Rosemary oil is potent, so it should always be diluted with a carrier oil before use. Here’s how to apply it.

1. Scalp massage: Mix a few drops of rosemary oil with a carrier oil like coconut or almond oil, then massage into the scalp.

2. Add to shampoo: Mix a few drops into your shampoo or conditioner for an easy way to incorporate it.

3. Overnight treatment: Apply diluted rosemary oil to the scalp before bed and rinse in the morning.

Can you use castor oil and rosemary oil together?

Yes! Combining castor oil and rosemary oil can give you the best of both worlds—moisture and scalp stimulation. Try mixing a few drops of rosemary oil into castor oil for a powerful hair mask.

 

Which oil is better for you?

So, which is better: rosemary oil or castor oil for hair growth? It depends on your hair needs.

 

Making the best (oil) choice for your hair

At the end of the day, the best oil is the one that works for you. Castor and rosemary oil for hair growth each have their own strengths, and whether you need deep hydration, scalp stimulation, or both, these natural oils can be powerful allies.

If you’re new to hair oils, start by testing one for a few weeks and tracking your results. If you’re feeling adventurous, mix them together and see how your hair responds. The key is consistency—healthy, strong hair doesn’t happen overnight, but with the right routine, you’ll start to see the difference.