rosemary oil vs castor oil next to each other

The two natural ingredients that are most often recommended for hair growth are castor oil and rosemary oil. But do they actually work? Is one better than the other? And what’s the best way to use them? Well, you’re going to get the answers to all of that – and more – in this article on castor oil vs rosemary oil for hair growth.

But before we get into the details, there is one thing to be aware of:

Although there is research showing that rosemary oil promotes hair growth, there aren’t similar studies for castor oil. However, there is anecdotal evidence showing that both oils promote hair growth. So, one oil isn’t better than the other. Rather, they can be used together for optimal hair growth.

Now, let’s dive Let’s get to it!

Note: this post contains affiliate links and I earn a commission (at no additional cost to you) if you use them to make a purchase.


rosemary plant and the essential oil

1. Improves androgenetic alopecia

Androgenetic alopecia is hair loss caused by androgens, aka male hormones. 

And according to a study done with 100 androgenetic alopecia patients, rosemary oil provides the same benefits as minoxidil (the main ingredient in products like Rogaine).

In the study, the participants were split into two groups. One group used 2% minoxidil and the other group used a 1% dilution of rosemary oil.

After 3 months neither group had any significant hair growth.

However, at 6 months (1, 2):

  • Both groups had noticeable hair growth and a reduction in hair loss.
  • The group using rosemary oil had less side effects. Most notably, rosemary oil didn’t produce the itching that typically occurs with minoxidil.

2. Increases blood flow to the scalp

According to a review that looked at all the studies done on rosemary oil, it seems that the oil can boost “microcapillary perfusion” (source).

This basically means that rosemary oil increases blood flow through the blood vessels that supply the scalp.

Since blood carries nutrients and oxygen, this is probably one of the main ways in which rosemary stimulates hair follicles.

3. May improve alopecia areata

Another potential benefit of rosemary oil for hair loss is in the treatment of the autoimmune condition, alopecia areata.

Interestingly, a small study done with 86 alopecia areata patients showed that a daily scalp massage of 4 essential oils improved symptoms (source).

The oils used for the study were rosemary, lavender, thyme and cedarwood.

4. Soothes scalp inflammation

Rosemary essential oil is often used as a natural remedy for itchy scalp, dandruff and other inflammatory scalp conditions.

Since rosemary has anti-inflammatory and antimicrobial properties, it’s not surprising that it can support scalp health.


castor seeds and oil

Compared to rosemary oil, there are no studies that have been done on castor oil and hair growth. So, castor oil’s popularity as a hair growth aid comes mainly from anecdotal reports (such as Youtube videos and discussions on forums like Reddit).

That said, castor oil is still a very beneficial carrier oil and can support hair growth in various ways, as listed below.

1. Improves length retention

Like all carrier oils, castor oil is excellent for sealing in moisture. The more your hair stays moisturized, the lower the chances that it dries out and breaks off.

So, ultimately, castor oil can help you retain more of the length that’s always grown out.

2. Antimicrobial and Anti-inflammatory

About 75-90% of castor oil is made of the fatty acid, ricinoleic acid (source).

This fatty acid has anti-inflammatory and antimicrobial properties that can support a healthy scalp.

Scalp is an important part of hair growth because everything from dryness and flakiness, to build up or infections can contribute to hair loss.

3. May improve blood flow to the scalp

Ricinoleic acid – the main active compound in castor oil – seems to be effective at dilating blood vessels.

When dilated, the amount of blood flowing through those vessels increases. This leads to more blood supply to the root of the hair.

This is potentially one of the reasons why some people experience hair growth with castor oil.


1. Choose the right type of oils

There are different types of castor oil and rosemary oils. Here’s a brief overview of your options:

  • Moroccan rosemary (aka rosemary 1,8 cineole) or Spanish rosemary (aka rosemary ct camphor): according to expert aromatherapist, Robert Tisserand, Moroccan rosemary is most likely better for hair growth.
  • Black castor oil and white castor oil: anecdotal reports show that both of these may help with hair growth. Whichever one you use, just make sure that it is cold-pressed.

2. Select the best dilution ratio

Based on the studies that have been done with rosemary oil, a 1% dilution is enough to produce results in hair growth. This is equivalent to 9 drops of rosemary oil for every 1 ounce of castor oil.

If the 1% dilution doesn’t produce the desired results, you can experiment with a 2%, 3% or 4% dilution. See dilution guidelines below.

Dilution RatioIngredients
1%9 drops rosemary oil and 1 ounce of castor oil.
2%18 drops rosemary oil and 1 ounce of castor oil.
3%27 drops rosemary oil and 1 ounce of castor oil.
4%36 drops rosemary oil and 1 ounce of castor oil.
This table shows the dilution ratios to use when mixing rosemary and castor oil for hair.

3. Apply the oils several times a week

To get the best results, apply your castor and rosemary oil blend every other night. Make sure to take a few minutes to massage it into the scalp after applying.

In addition, keep these tips in mind: 

  • Always apply castor oil to damp hair, focusing mainly on the ends of your hair. This will seal in moisture. Avoid applying it to dry hair because this actually dries out your tresses.
  • You can apply white castor oil to your strands and scalp. However, for black castor oil, some experts suggest using it on your strands only. If you do apply black castor oil to your strands, you should follow it up with another sealant (source).
  • Although all hair types can benefit from castor oil, it’s particularly beneficial for curly-kinky hair. For this hair type, you can use it as a prepoo treatment or as a sealant whenever you moisturize your hair.
  • When applying castor and rosemary oil to your scalp, you only need a small amount (since castor oil is quite thick). Make sure to take a few minutes to massage it in.
  • If you have fine hair, castor oil may be too heavy (and sticky!) for you. So, consider mixing it with lighter oils like grapeseed, almond or jojoba.


1. Plant Therapy Rosemary 1,8 Cineole

bottle of rosemary 1,8 cineole

This organic rosemary oil is a personal favorite for my DIY projects. In addition, Plant Therapy has a wide variety of organic (and non-organic) essential oils to choose from.

Lastly, if you are ever curious about the quality of their oils, you can see GCMS reports on their website.

The GCMS report is a very basic report that validates the quality of the oil and it is done by a third party.


2. Eden’s Garden Moroccan Rosemary

bottle of moroccan rosemary oil

Eden’s Garden is another brand that I rely on for essential oils because they have a massive selection.

Similar to Plant Therapy, they also provide GCMS reports on their website for those of us want to geek out on that information 🙂


3. Sunny Isle Jamaican Black Castor Oil

bottle of sunny isle black castor oil

This oil is made via the traditional process of roasting castor seeds, grinding them and finally, boiling them. The end result is a rich, dark oil that is perfect for your hair (and eyebrows too, by the way!).


4. Aura Cacia Castor Oil

Aura Cacia is a company that is known for providing high quality oils carrier and essentials oils. And this cold-pressed, organic is no exception. As an added perk, this castor oil comes in a dark bottle, which helps to protect it from the damaging effects of light.



What are the side effects of castor oil on hair?

Castor oil is a very slow absorbing oil. This means it sits on the scalp and could clog pores. This can lead to itching and in some cases hair breakage. 

In addition, since castor oil can clog pores, it could also worsen dandruff. 

How long does it take for rosemary oil to grow hair?

According to some of the studies that have been done comparing rosemary oil with minoxidil, it can take about 6 months to see hair growth.

Can I apply rosemary oil directly to hair?

Rosemary essential oil should never be applied to the hair directly. Instead, it should be diluted in a carrier oil like grapeseed or jojoba oil. This minimizes the risk of irritation from the rosemary oil and also slows down evaporation of the essential oil (which means your scalp can absorb more of the oil).

How long does it take for castor oil to grow hair?

Anecdotal reports from people who’ve successfully used castor oil for hair growth shows that it can take about a month of regular use to start seeing results.


Because rosemary oil is an essential oil, and castor oil is a carrier, they support the health of the hair in different ways. 

When used correctly, both ingredients are generally considered safe and they’re likely to help you reach your hair growth goals.

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