Quick Hair Growth Oil Recipe: Castor & Rosemary DIY Treatment

I bet you have endless questions about hair growth oils.

I certainly do. Still learning from all the research, and finding out more and more as I go along. Stuff you’d want to know.

And, yes, you’ve heard castor oil and rosemary oil can help with hair growth. But does castor oil actually work? Is rosemary really as good as they say? Is this all natural trend after trend? (I hate those).

I’ve always lost quite a bit of hair, and menopause isn’t helping. Some days I care, most days I’ve accepted it.

I really want to test these treatments on myself properly and create a whole project around treating my scalp naturally over the next year. I might blog abut it but I first need to find the time (and I will, I always do).

Let me share with you what I know will actually help and what’s just wishful thinking.

Disclaimer: below you will find affiliate links. If you purchase through them I might make a commission at no extra cost to you.

Here’s what this oil can (and can’t) actually do for your hair

Before we get to the recipe, let’s talk about what’s actually happening when you use these oils.

What you might notice:

• Hair that looks thicker and shinier (this is real according to scientific research)
• Less breakage from improved moisture
• A healthier-feeling scalp
• Hair that seems fuller over time (aloe vera actually gives me this result).

What’s probably NOT happening:

• Brand new hair sprouting from previously bald spots
• Dramatic growth overnight
• Reversal of genetic hair loss patterns

The benefits you’ll see are mostly about protecting and optimising the hair you already have, rather than creating new follicles where none exist.

Still good news though.

The two lovely ingredients and what they’re really doing for your hair

Castor oil is BRILLIANT at making your hair look thicker (but it’s not creating new growth)

Ok, let’s address the elephant in the room. Castor oil is everywhere in hair growth recipes, but here’s what’s actually going on.

Castor oil is incredibly thick and rich in ricinoleic acid, a fatty acid that can help moisturise your scalp. But (and this is important) there’s no solid clinical evidence that it actually makes hair grow faster.

What it can do is make your existing hair look and feel THICKER because it literally coats each strand. That’s it. Think of it like a conditioning treatment that creates the appearance of fuller hair whilst reducing breakage. And, yes, that is a fact.

(The one tiny study that showed positive results was done on isolated hair follicles in a lab, not on actual human scalps. So whilst castor oil isn’t harmful for most people, don’t expect miracles. Here it is if you want to check it out).

Rosemary oil might help with circulation (though the research is somehow questionable)

Now, rosemary oil is where things get more interesting but also a little more complicated.

There’s one study from 2015 that found rosemary oil worked as well as minoxidil (the active ingredient in Rogaine) for hair growth.

Unfortunately the study has been heavily criticised by researchers for having serious methodological problems and calculation errors. The lead author has also had multiple papers retracted, which raises red flags about the reliability.

What rosemary oil might actually do:

• Improve blood flow to your scalp (this part can be genuine)
• Provide anti-inflammatory benefits
• Potentially inhibit some hormones linked to hair loss

The circulation boost is real. And, anything that creates a healthier scalp environment is worth considering. Just don’t bank on it being a miracle cure, as per usual with natural ingredients.

See below my comparative summary table

Oil/Combination	Main Findings (2023–2025)	Level of Evidence	Benefit Type
Castor oil	Boosts keratin, moderate follicle growth effects	Mixed, animal and human experiments	Thickness, length
Rosemary oil	Improves growth, comparable to minoxidil	Multiple clinical trials	Density, regrowth
Rosemary + Castor oil	Measured growth/thickness/fall reduction	2025 controlled study	All major parameters
Coconut oil (comparator)	Hydrating, less regrowth impact	Used as control in studies	Hydration

Here’s my simple recipe that maximises benefits without the hype (so something you can actually trust)

Here’s how to make a hair treatment that actually works without all the marketing fluff.

You’ll need:

• 2 tbsp castor oil (cold-pressed if possible – aff link)
• 1 tbsp carrier oil (jojoba or sweet almond work beautifully – both aff links)
• 4-5 drops rosemary essential oil – aff link
• Dark glass bottle for storage, you can find them here – aff link

Why these proportions: The carrier oil makes the thick castor oil easier to apply and wash out (and, yes, it is VERY thick). The rosemary is diluted to about 2%, strong enough to potentially help, gentle enough to avoid irritation!

Making this hair oil is surprisingly straightforward

1. Combine the oils in your glass bottle
2. Shake gently to blend everything together
3. Store in a cool, dark place (it’ll keep for about 6 months – up to 1 year in the refrigerator.)

Very simple!

How to apply this oil properly (technique matters by the way)

Application method:

1. Part your hair in several sections to expose your scalp
2. Apply 1-2 teaspoons directly to your scalp (not just your hair lengths)
3. Massage gently with your fingertips for 2-3 minutes
4. Leave for 30-60 minutes (longer isn’t necessarily better)
5. Shampoo thoroughly. This might take two washes because castor oil is stubborn

How often: Once or twice a week maximum. More than this can actually clog your follicles or make your hair greasy.

Important timing note: Give it at least 6-8 weeks of consistent use before deciding if it’s working. Hair growth is slow, and any real changes take time to become visible.

Watch out for these warning signs that mean you should stop immediately

Red flags to stop immediately:

• Scalp irritation or itching that doesn’t go away
• Increased hair shedding (this can happen if you massage too vigorously)
• Clogged pores around your hairline
• Hair that becomes impossible to wash clean

Patch test first: Always test a small amount on your inner wrist 24 hours before using on your scalp, especially if you have sensitive skin.

Let’s talk realistic expectations (because I don’t want you to be disappointed)

I’ve seen too many people get disheartened because they expected dramatic results from DIY treatments.

What success actually looks like:

• Hair that breaks less when you brush it
• A scalp that feels healthier and less tight
• Existing hair that appears fuller and shinier
• Possibly some improvement in thinning areas over many months

What won’t happen:

• Reversal of pattern baldness
• New hair in completely bald spots
• Overnight transformation

My honest thoughts on what this treatment can actually achieve

This hair oil blend is a lovely, natural way to pamper your scalp and potentially support the health of your existing hair. The rosemary provides a pleasant tingle and may offer some circulation benefits, whilst the castor oil gives your hair a conditioning boost.

Just remember: consistency beats intensity every time. A simple routine you can stick to will always trump an elaborate treatment you do once and forget about.

If you’re dealing with significant hair loss, it’s worth chatting with a dermatologist or trichologist. Sometimes the most loving thing you can do for your hair is get professional guidance alongside your DIY treatments.

But for general hair health and that satisfying feeling of nurturing your scalp with natural ingredients this blend is a gentle, affordable place to start.

Storage tip: Pop it in a dark glass bottle and keep it somewhere cool. It should stay fresh for about 6 months.

Give it a try, be patient with the process, and remember that healthy hair is a marathon, not a sprint.

Love,
Patri xx

Resources

1. Padmavathi S, Nagarajan R, Mahendiran B, Manoharan S, Ranganathan D, Sankaranarayanan S, et al. Rosmagain™ as a Natural Therapeutic for Hair Regrowth: A Clinical Efficacy and Safety Study of Rosemary Oil Formulations in Comparison with Coconut Oil. J Cosmet Dermatol. 2025 Jun 12 [cited 2025 Sep 21]. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC12256010/
2. Borah P, Das R, Choudhury P, Bhattacharjee S. Design, Formulation and Evaluation of Herbal Hair Oil using Coconut Oil and Castor Oil Infused with Different Herbs for Hair Growth. Res J Top Cosmet Sci [Internet]. 2025 [cited 2025 Sep 21];16(1). Available from: https://rjtcsonline.com/HTML_Papers/Research%20Journal%20of%20Topical%20and%20Cosmetic%20Sciences__PID__2025-16-1-5.html
3. Lamichhane A, Subedi L, Paudel A. Unlocking the Cosmetic Potential of Castor Oil: A Review. Zenodo [Internet]. 2024 [cited 2025 Sep 21]. Available from: https://zenodo.org/records/15448725
4. The effectivity of castor oil as hair grower. Academia.edu [Internet]. 2018 [cited 2025 Sep 21]. Available from: https://www.academia.edu/37295931/CONTROLLED_EXPERIMENT_DESIGN_TABLE_TITLE_THE_EFFECTIVITY_OF_CASTOR_OIL_AS_HAIR_GROWER
5. What is the scientific evidence for rosemary and hair growth? Consensus.app [Internet]. 2023 Dec 31 [cited 2025 Sep 21]. Available from: https://consensus.app/questions/rosemary-and-hair-growth/
6. Dugan B. How to use rosemary oil for hair growth. Medical News Today [Internet]. 2025 May 28 [cited 2025 Sep 21]. Available from: https://www.medicalnewstoday.com/articles/319444
7. Nguyen M. Does rosemary oil work for hair growth? The science explained. Lab Muffin [Internet]. 2024 Aug 25 [cited 2025 Sep 21]. Available from: https://labmuffin.com/does-rosemary-oil-work-for-hair-growth-the-science/