If your high porosity hair feels like it grows and grows but never gets longer, you are not imagining it, and you are not doing everything wrong. High porosity hair is fragile, and it tends to break at the ends about as fast as it grows at the scalp. So the goal is not really to make your hair grow faster; it is to keep more of the length you already grow.
I worked through the science of this with my friend, a hair scientist and cosmetic formulator with a PhD in chemistry, and I have lived it: years of bleaching and heat left me with thinning, breaking curls before I turned it around.
Short answer: growing high porosity hair comes down to length retention. Support a healthy scalp so hair grows in well, use the few growth actives that actually have evidence, feed growth with a balanced diet, and above all protect your fragile lengths from breakage. If you want the full care and ingredient breakdown, that lives in my complete high porosity hair guide; this post is about growth and keeping length.
Does High Porosity Hair Grow Slower?
Not at the root. Hair growth happens at the follicle in your scalp, and that pace, roughly half an inch a month on average, is set by your biology, not by your porosity.[3] High porosity hair only seems to grow slowly because it is damaged and breaks easily, so you lose length at the ends about as fast as you gain it up top.[1,2] That reframes the whole problem: you are not trying to speed up the follicle, you are trying to stop the breakage. Almost everything below is about retention.
If your hair is actually on the other end of the spectrum, the approach differs in a few key ways; see how to grow low porosity hair.
Growth Starts at the Scalp
Every strand you will ever grow starts at a follicle in your scalp, so a clean, healthy scalp is the foundation.[3] When product residue, oils, dead skin, and sweat build up, the scalp environment suffers. A gentle, regular cleanse keeps it clear; you do not need a harsh weekly clarifying ritual for this, just effective washing.
If buildup is a recurring issue for you, see scalp build-up: what it is and how to treat it, and for cleanser picks, the best shampoos for high porosity hair. A light scalp massage while you cleanse feels good and is easy to keep up; treat it as routine care, not a magic growth trick.
Growth Actives That Have Real Evidence
Most things marketed for hair growth do very little, and one of the most hyped does not hold up the way the internet claims. Here is what the evidence actually supports.
Minoxidil is the only topical scientifically proven to regrow hair and slow hair loss. It is approved by regulators for pattern hair loss, applied to the scalp, and takes a few months of consistent use to show and maintain results. Because it is a drug with real considerations, talk to a dermatologist before starting it. When my daughter dealt with hair loss, minoxidil made a clear difference for her; I wrote about that in my Hers minoxidil review.
Rosemary oil is the one I need to correct, and I want to be honest: I used to believe in it too. If you have been spritzing rosemary oil or water hoping for growth, you are not alone, and there is no shame in it; the claim is repeated so often it sounds settled. It is everywhere online right now, usually framed as working as well as minoxidil. That claim traces to a single small trial,[4] and there are only two published studies on rosemary and hair growth in total,[4,5] both done in people with androgenetic alopecia. Here is how my hair scientist put it:
From my hair scientist and cosmetic formulator (PhD in chemistry):
There is no solid scientific evidence that rosemary oil increases hair growth. People point to one trial that found it comparable to 2 percent minoxidil, but that study is not reliable; it is full of methodological red flags. Both of the studies that exist were done in people with alopecia, and neither actually shows that rosemary causes hair to grow, or that the results would carry over to normal hair growth and loss. Rosemary water is even weaker: when the leaves are boiled, the compounds people are chasing vaporize off, so the water is largely left without them. Minoxidil is the only topical with real evidence behind it.
So if you enjoy using rosemary oil and your scalp likes it, it is unlikely to hurt at a sensible dilution, but do not count on it to grow your hair, and do not bother with rosemary water as a growth treatment. Put your effort into the things in this post that actually move the needle: a healthy scalp, less breakage, and minoxidil if hair loss is your concern.
And if you are wondering why my advice on this has changed: that is science working the way it should. Science is self-correcting, built on continuous discovery. As new observations, experiments, and better tools emerge, established ideas get refined, updated, or replaced so they reflect reality more accurately. Updating what I tell you when the evidence updates is not me being wishy-washy; it is the whole point.
Feed Hair Growth From the Inside
Hair is built from what your body has to work with, so a balanced diet with enough protein, iron, zinc, and vitamins supports a normal growth cycle. If you suspect a deficiency, the most useful step is bloodwork and a conversation with your doctor or a dietitian, since correcting a real deficiency (iron, for example) can genuinely help, while loading up on supplements you do not need usually does not. Biotin is the classic example: it only helps if you are actually deficient, which is uncommon, so do not count on a biotin pill alone to grow your hair.
Protect Your Length (Where Growth Is Won or Lost)
This is the heart of growing high porosity hair. Because the strand is fragile, the length you keep is decided by how gently you treat it day to day.
Detangle Gently
High porosity hair breaks most easily when it is wet and under tension, so detangle slowly, on conditioner-coated hair, with a wide-tooth comb, a detangling brush, or your fingers. Rushing this step is one of the fastest ways to undo months of growth. Prolonged soaking also stresses porous strands, which is the swelling behind hygral fatigue, so do not let hair sit waterlogged longer than it needs to.
Trim and Dust the Ends
This feels backward when you are trying to gain length, but it is essential. Damaged ends split and the split travels up the strand, costing you more length than a small trim would. Dusting the very ends every ten to twelve weeks, ideally around your curly haircut appointments, keeps damage from spreading and helps you retain length over time.
Protective Styling and Low Manipulation
Styles that tuck the fragile ends away and keep your hands out of your hair reduce daily wear. Just keep them loose; tight styles that pull at the hairline trade one kind of damage for another.
Switch to Satin and Silk
Cotton creates friction that roughs up and snaps fragile strands. Swap to a satin or silk pillowcase, bonnet, or scarf at night, use smooth hair ties that do not crease or snag, and dry with a microfiber towel or an old t-shirt instead of a terry towel.
Limit Heat, Chemical Services, and Sun
Every flat iron pass, bleach session, and long sun exposure wears the cuticle down further and adds breakage,[1,2] which is the opposite of retention. Stretch out or reduce heat and chemical services where you can, and if you do use heat, keep it as low as works. If heat has already taken a toll, see how to restore curls after heat damage.
Manage Hard Water
Hard water leaves mineral deposits that make hair feel rough and harder to manage over time. If you are in a hard-water area, a shower filter is a low-effort upgrade that many people find makes their hair easier to keep healthy.
Your Wash-Day Routine Still Matters
Retention is not only about handling; a solid wash-day routine keeps the strand conditioned and less breakage-prone between styles. The short version: cleanse gently, condition for slip, deep condition when hair feels rough, and use protein when the hair feels weak so it breaks less. I cover the full routine and the ingredients to look for in the complete high porosity hair guide, with deeper dives on deep conditioners, leave-ins, oils, and protein treatments. Use those as your reference so this routine supports growth instead of causing breakage.
Managing New Growth
As healthier hair grows in, treat it gently from the start: keep the scalp clean, keep up the protective habits above, and be patient. New growth is the most undamaged hair you have, so the goal is simply to not wear it down the way the old lengths got worn down. Consistency over months is what shows up in the mirror, not any single product.
My Own Experience With Thinning and Regrowth
I went through this myself. In the early stages of my healthy hair journey, years of bleaching, heat, and rough handling left my curls severely damaged and thinning, especially at the ends, and the emotional side of that was real. What turned it around was not a miracle product; it was cutting the damage, protecting my length, and staying consistent. The hair grew the whole time; once I stopped breaking it off, I finally started keeping the length.
And here is where staying consistent got me. My curls bounce back full and healthy now. But curls shrink, so a curly photo genuinely hides how much length I am holding onto.
Stretched out, the difference is obvious. I had never had waist-length hair before in my life, because it always broke off before it could ever get there. That is the entire point of this post: I did not start growing faster, I stopped losing the length I was already growing.
The same hair, stretched straight. This was the first time I had straightened it in 8 years; I did it once to show the true length. Curls hide it, but this is what stopping the breakage got me: waist-length for the first time in my life.
Frequently Asked Questions
Does high porosity hair grow slower than other hair?
No. Growth happens at the follicle and runs at roughly the same pace regardless of porosity, about half an inch a month on average. High porosity hair just loses length to breakage faster, so it looks like it is not growing. Fix the breakage and the length shows up.
How fast does hair grow?
Around half an inch, or about a centimeter, per month on average. You cannot meaningfully speed up the follicle, but you can keep far more of what it produces by reducing breakage.
Does rosemary oil really grow hair?
A six-month randomized trial found rosemary oil worked about as well as 2 percent minoxidil for pattern hair loss, with less scalp itching. The evidence is promising but limited, and it takes months of consistent use, so treat it as a reasonable option, not a guarantee.
Can I regrow thinning ends or edges?
Thinning caused by breakage usually fills back in once you stop breaking the hair and let it grow. Thinning from the follicle itself, or sudden shedding, is worth taking to a dermatologist, since that is a different problem from surface damage.
How often should I trim if I am trying to grow my hair?
Dusting the very ends every ten to twelve weeks is plenty for most people. Trimming away damaged ends prevents splits from traveling up the strand, which actually helps you retain length rather than lose it.
References
- Syed AN, Ayoub H. Correlating porosity and tensile strength of chemically modified hair. Cosmet Toilet. 2002;117(11):57–64.
- Zviak C. The Science of Hair Care. Taylor & Francis; 1986.
- Harkey MR. Anatomy and physiology of hair. Forensic Sci Int. 1993;63(1–3):9–18.
- Panahi Y, Taghizadeh M, Marzony ET, Sahebkar A. Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial. Skinmed. 2015;13(1):15–21.
- Murata K, Noguchi K, Kondo M, Onishi M, Watanabe N, Okamura K, Matsuda H. Promotion of hair growth by Rosmarinus officinalis leaf extract. Phytother Res. 2013;27(2):212–7.
