How to Dilute Rosemary Essential Oil for Hair

Herbalists have used rosemary tea to make hair glossier for at least two thousand years. However, since oil and water don’t mix, if you want to try and use essential oils to do the same, you will require either alcohol or an emulsifier to bind them together. Rosemary can, of course, be used with a carrier oil and used as a hair masque.

However, rosemary is an oil with several safety issues,  so in this article, we’ll look at some solutions to dilute rosemary essential oil for hair and recap any times that it might be better to avoid it.

Why Use Rosemary on Your Hair

The number of scientific studies proving essential oils help your hair to grow is very few. However, as stated, traditional medicines have used botanical extracts to protect skin and hair from the elements, probably as long as there have been humans..

In 1998, a trial was performed in a Scottish Dermatology outpatients ward.  The seven-month-long randomized, double-blind, controlled trial consisted of 86 patients confirmed as suffering from alopecia areata. Patients were split into two groups, assessed at recruitment and at 3 and 7 months.

Each group was to massage their scalps daily, one group had a simple mixture of grapeseed and jojoba carrier oils, and rosemary, thyme, cedarwood, and lavender essential oils were added to the other group’s blend. 

The results of both groups were assessed using photographs and the condition improved in both groups throughout the trial, but the essential oil group performed significantly better. 

Six people’s hair had started to grow in the control group, which equated to 15%) in the essential oil group. However, the essential oils group did much better, with 19 people reporting differences. That equated to 44% of the essential oils group.

Incidentally, you can find out more about this and other studies on a page we wrote about the best essential oils for hair growth, where we also talk about helpful carrier oils.

Limitations of Using  Essential Oils for Hair Growth

One of the things you'll need to consider when you're thinking about how to dilute rosemary essential oil for hair is time. 

Essential oils need around nineteen minutes to travel through the skin and into the bloodstream to start working. 

If you put it into a shampoo or a normal conditioner, you will wash it off before it has a chance to start working. 

One of the best ways of creating an emulsifying hair mask is to use something thick and gentle that you can leave on for a while. Henna wax works tremendously well for this. Simply work out your dilutions and mix yourself a whole pot. Then you can leave it on as long as you like and thoroughly rinse it.

Another great way to use rosemary is to use a thick carrier, like coconut MCT or castor oil, and leave them on for half an hour or so before shampooing out. If you feel brave, you could leave it on overnight for bed, but if you think about the energetics of rosemary, that’s not a great plan. Rosemary is refreshing and stimulating. It works well in the mornings but is not great if you want to sleep.

Safety of Using Rosemary Essential Oil for Hair Growth

Rosemary is an extremely potent and somewhat overwhelming oil. It is not safe for everyone. It may be worth you checking out our post about what rosemary oil is good for to understand this bit better. 

Essential oils do not have side effects but many main effects. Rosemary pushes the energy around the body hard. It increases your heart speed and blood pressure, so if you already suffer from high blood pressure, you might want to give this oil a miss. Cedarwood might be better for you, for example.

Likewise, rosemary is full of a chemical group called ketones. Ketones are wonderful for breaking stuff down, so aromatherapists use them to break down catarrh and scar tissue, for example. But ketones can also have a neurotoxic effect on the brain. For some people who have epilepsy, this can be problematic, and the same applies to those with psychosis, schizophrenia, or other delusory complaints. 

In any of these conditions, we can see how sitting and pouring rosemary oil directly into our scalps may be foolhardy.

In addition, we would not advise using any essential oils during the first sixteen weeks of pregnancy. Rosemary oil would be fine after that. We’d recommend reducing the dilution to 2%.

How Much Rosemary Oil to Use

The maximum dilution of rosemary essential oil is 3% 

Dilution is so much easier in metrics than it is in imperial measurements!

A great guide is that a teaspoon holds approximately 5ml of oil which equals about 100 drops of carrier oil.

If you work with teaspoon measures, dilution becomes simple.

    • 3% dilution of Rosemary Oil in a teaspoon of Carrier Oil is 3 drops 
    • 2% dilution for someone who is weakened (Has been ill, if frail and elderly)
    • 1 drop = 1% dilution.

Easy peasy lemon squeezy!

Note too that we speak here of maximum dilution. That is the maximum you can add safely, but adding less would be perfectly fine.

If we decided to make a big wad of hair oil, we might say 100mls of oil; we can use 3% dilution, that’s a whole 3mls. There is no way you’d want to use that much. It would smell way too strong, and it is getting expensive.

If in doubt, start with less. You can always add a little more.

Carrier Oils to Dilute Rosemary Essential Oil for Hair 

While the jury is still out on whether MCT Coconut oil improves hair growth, it’s accepted that any massage stimulating the scalp's blood supply probably does. Its impulsive action and the light, non-greasy texture make it a fabulous option for scalp treatments because it will wash out much easier afterward.

Despite the lightness of Coconut MCT oil, it is still incredibly rich, so avoid using it on hair that already leans towards greasy. Instead, exploit its nourishing action on dry, curly, frizzy, and treated hair. Again, its easy-to-wash-out-action means less emphasis on shampooing later, which is great news for lightened and colored hairs.

Since it is now an ester rather than an oil and is lighter, it works wonderfully in volumizing preparations. Other oils, while nourishing, can leave heavier residue and thus flatten the hair.

Ayurveda says that hair loss can be attributed to excess heat in the follicles (often brought about by stress), and castor oil has long been used to preserve a lovely thick set of braids. But, as yet, there is no clinical evidence to support or disprove this claim. In the same way, Ayurvedic castor oil is used to thicken and deepen the hair’s natural color and to guard against graying and loss of pigmentation.

Again, as yet, this has not been proved or disproved. Nevertheless, anecdotal evidence from users reports as much as three to five times their normal hair growth when they have used castor oil twice a week for a month.

Rosemary Henna Conditioner

Method of use: Use a good handful of damp hair. Wrap hair in a warm towel. Leave on for around twenty minutes. Rinse out thoroughly, ideally with a strong rosemary tea. 

Safety: Not suitable for use in the first 16 weeks of pregnancy. Do not use rosemary if you have schizophrenia, psychosis, or delusory complaints. It is not recommended for people with high blood pressure or epilepsy.

Rosemary Scalp Massage

Method of use: Massage the scalp for five minutes, then wrap your head into a warm towel. Leave on for an hour. Shampoo and rinse thoroughly, ideally with a strong rosemary tea.

Safety: Not suitable for use in the first 16 weeks of pregnancy. Do not use rosemary if you have schizophrenia, psychosis, or delusory complaints. It is not recommended for people with high blood pressure or epilepsy.

Rosemary Tea

So simple. Ideal if you have trimmed your rosemary plant. Cut into small bits and add to a saucepan of water. Bring it to a boil, then turn it down to a slow simmer for about 20 mins. 

Leaving it to cool overnight will make it even stronger. 

This is best made on the same day as washing your hair or the day earlier. 

Use it cool to close down the shafts of the hair and the hair follicles. 


Learning how to dilute rosemary essential oil for hair is all about thinking about your safety. If none of the contraindicated conditions apply, simply add to oil or thick, leave-in conditioner and be prepared to wait for a while. Remember, it will take at least 20 minutes to do any good.

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