TL;DR
Our No. 02 Botanical Serum leads with rosemary leaf extract (the one botanical here with a real, if imperfect, human hair trial behind it) and rounds it out with a chlorella-and-spirulina marine blend, ginger, licorice and baicalin, and vitamins C and E, most of which are in the formula for the scalp environment and sensory experience rather than proven hair outcomes. This is a plant-first serum for people who prefer botanicals over synthetic peptides. It is not a drug, it doesn't regrow hair, and we'll tell you plainly which ingredients have hair evidence and which don't.
Ingredient explainers on beauty sites usually run one direction: every component gets a glowing paragraph, every extract "boosts growth," and nothing is ever just along for the ride. That's not useful, and it's not honest. So here's the opposite: an ingredient-by-ingredient walk through our No. 02 Botanical Hair Growth Serum ($55), graded by what the human evidence actually supports, with the weak cases labeled weak.
Unfurl is a hair-wellness brand, and No. 02 is a plant-first daily scalp serum: it occupies the same morning slot as our peptide serum but leads with botanicals instead of synthetic peptides. Because this is a product-led article, we're holding it to the strictest version of our rules: structure/function claims only, and a clear line between "this ingredient has human hair data" and "this ingredient is here for the scalp environment and the experience of using it."
What is No. 02, and who is it for?
It's a leave-in morning serum built around plant actives, for people who specifically want a botanical formulation rather than the biomimetic peptides in our No. 01. Same slot in the routine, same 30-day-ish bottle, same structure/function register, but a different philosophy about what goes in it. If you're the kind of person who reads a label and prefers rosemary and algae to sh-Polypeptides, this is the one built for you.
What it is not is a drug or a growth guarantee. Like every topical that works with the hair cycle, it's a consistency product: eight to twelve weeks of daily use before you evaluate, month four for maximum effect. It supports the appearance of fuller-looking hair and a healthy-looking scalp. It does not regrow, treat, or prevent anything; those are drug claims, and this is a cosmetic. With that frame set, let's go ingredient by ingredient.
Rosemary leaf extract: the one with real human hair evidence
Evidence grade: strongest in the formula, but read the trial carefully. Rosemary is the lead active, and it's the only ingredient here with a genuine head-to-head human hair trial behind it. In a 2015 study, Panahi and colleagues randomized 100 people with androgenetic alopecia to rosemary oil or minoxidil 2% for six months and found comparable improvements in hair count between the two groups, with less scalp itching in the rosemary arm. That's a real result, and it's the reason rosemary leads this formula rather than decorating it. There's a plausible mechanism underneath it too: Murata and colleagues (2013) reported that rosemary extract inhibits 5-alpha-reductase in preclinical models, the same enzyme pathway that drives androgenetic thinning. That is lab-and-animal evidence, not proof in people, but it's a reason the ingredient is more than a pleasant scent.
Now the honest limitations, because they matter and the marketing version of this study usually hides them:
- It was comparative, not placebo-controlled. There was no placebo arm; both groups got an active treatment. So the study shows rosemary tracking with minoxidil, but it can't fully rule out that both groups partly improved for reasons unrelated to either (regression to the mean, the massage of application, expectation). A placebo-controlled trial would be more convincing, and it hasn't been done at this scale.
- It studied a rosemary oil preparation, not our serum. The trial used a specific rosemary essential-oil preparation applied to the scalp. Our No. 02 uses rosemary leaf extract in a serum base. Ingredient evidence is not finished-product evidence; we won't blur that line, and you shouldn't let any brand blur it for you.
- A single trial is a starting point, not a settled science. One study, however well-designed, is one study.
So the honest read: rosemary is the best-supported active in this serum, the trial is real and worth knowing, and it's still a small, comparative, single study of a different preparation. That's a good ingredient to lead with and a bad one to oversell. We go deeper on this exact study (and the minoxidil comparison) in our forthcoming rosemary oil vs minoxidil evidence breakdown.
Chlorella and spirulina marine blend: nutrient-dense, but not proven for hair
Evidence grade: weak for hair specifically; say so. The marine blend is chlorella and spirulina, two algae that are genuinely nutrient-dense: they carry protein, minerals, and antioxidant compounds, which is why they show up across wellness formulations. That nutritional density is real and is the honest reason they're here: they contribute to a well-rounded topical antioxidant and conditioning profile for the scalp surface.
Here's the part most brands skip: human evidence that topical chlorella or spirulina grows or thickens hair is essentially absent. There isn't a body of controlled human hair trials to point to. We're not going to invent one or gesture at a mouse study as if it were proof for your scalp. These algae are in the formula for scalp-environment and antioxidant reasons, not because there's clinical hair-growth data behind them. If a competitor tells you spirulina "stimulates growth," ask them for the human trial; there isn't a persuasive one.
Calling this out is the whole point of an honest ingredient explainer. A component can be a reasonable, high-quality inclusion for the scalp environment and have no proven hair-growth effect at the same time. Both things are true of the marine blend.
Ginger: for the scalp environment and the senses, not for growth
Evidence grade: do not claim growth, because the lab data actually cuts the other way. This is the ingredient where honesty matters most, because the intuitive story ("warming, traditional, good for circulation, therefore grows hair") runs straight into inconvenient science. Ginger's main active, 6-gingerol, has in-vitro and animal data that is ambiguous at best and, in the most-cited study, negative for hair growth.
In 2013, Miao and colleagues published work in PLOS One showing that 6-gingerol suppressed hair-shaft elongation in cultured human follicles and inhibited the dermal papilla cells that support growth; in mice, it prolonged the resting phase rather than promoting growth. The authors concluded 6-gingerol is a poor candidate for stimulating hair and might even suppress it. That's not a result we're going to hide behind a vague "energizing botanical" claim.
So why is ginger in the formula at all? For the reasons it honestly earns: it contributes to the scalp-environment profile and to the warming, aromatic sensory experience of using the serum: the smell, the slight warmth, the feel that makes a daily ritual something you'll actually keep doing. That sensory-and-adherence role is a legitimate reason for an ingredient to exist in a cosmetic; daily consistency is, after all, the active ingredient in any scalp routine. What ginger is not here to do is grow hair, and we won't claim it does. If you see a brand crediting ginger for regrowth, the strongest lab evidence points the other way.
Licorice and baicalin: scalp-soothing and antioxidant support
Evidence grade: reasonable for scalp comfort and antioxidant support; not a growth claim. Licorice root and baicalin (a flavonoid from Scutellaria baicalensis, the same skullcap family botanical in our No. 01) are here as soothing and antioxidant actives for the scalp surface. Both have a long cosmetic track record as calming, anti-irritant ingredients, and baicalin in particular shows up in the cosmetic-science literature as a scalp-conditioning antioxidant.
The honest framing: these support a comfortable, healthy-looking scalp environment, the kind of calm, non-reactive surface that makes a daily topical pleasant to use. That's a real and worthwhile job. It is not the same as a hair-growth claim, and we're not making one for them. Antioxidant support on the scalp is a defensible cosmetic rationale (the dermatology literature on oxidative stress and follicle aging is why), but "supports a healthy-looking scalp" is the honest ceiling, not "regrows hair."
Vitamins C and E: antioxidant support, honestly labeled
Evidence grade: established antioxidants; supporting role, not a growth driver. Vitamin C (ascorbic acid) and vitamin E (tocopherol) are well-characterized antioxidants that round out the formula. In a topical serum, their role is antioxidant support for the scalp environment and formula stability; vitamin E also helps protect the oils in the formula from oxidation. That's a genuine, unglamorous, useful job.
What they are not is a topical growth treatment. Taking vitamin C or E for hair only makes sense in the rare case of a genuine dietary deficiency, which is a nutrition question, not a serum one, the same "correct a real deficiency, don't supplement blindly" logic we apply to protein and diet, ferritin, and vitamin D. In the serum, C and E are supporting antioxidants, labeled as exactly that.
So what does the whole formula honestly do, and who should skip it?
Put together: No. 02 is a plant-first daily serum led by the one botanical here with real human hair data (rosemary), supported by ingredients chosen for the scalp environment, antioxidant profile, and sensory experience (the marine blend, ginger, licorice, baicalin, vitamins C and E). Used daily and consistently, the plant-first botanical serum supports the appearance of fuller-looking hair and a healthy-looking scalp over eight to twelve weeks. That's the honest claim, and it's the whole claim.
Here's the two-sided summary, plainly. This is not finasteride, it is not minoxidil, and it will not lower your DHT or regrow hair the way a drug can. Of its actives, one (rosemary) has a real but limited human hair trial, and the rest are formulated for the scalp environment and the experience of the ritual rather than for proven growth. If that honest profile is what you want in a botanical serum, it's a well-built one. If you wanted a clinically proven growth treatment, no cosmetic serum (ours or anyone's) is that, and you should talk to a dermatologist about drugs.
Who should choose No. 01 instead: our full peptide versus botanical serum guide walks this fork in detail, but in short, if your thinning is more clearly androgenetic (a widening part or crown, a family pattern) and you want the ingredient with a DHT-pathway rationale, the peptide-led No. 01 serum leads with five biomimetic peptides plus saw palmetto, worth reading about in our saw palmetto and DHT evidence piece and against the backdrop of the midlife hair shift. Choose No. 02 if you specifically prefer a plant-first formula and a warmer, more botanical daily ritual. You can compare both in the serums collection, and if you'd rather layer an overnight step, the overnight hair oil is a separate night-slot product, not a substitute.
Who this isn't for at all: anyone with sudden, patchy, or rapid loss (see a dermatologist), anyone expecting a two-week transformation, and anyone who'd rather have a drug's evidence base than a cosmetic's. Not sure which serum fits your scalp? Take the hair quiz: 90 seconds, and it maps part width, shedding, and scalp feel to a single starting recommendation.
Frequently asked questions
Does the rosemary in this serum actually work for hair?
Rosemary is the best-supported active in the formula: Panahi and colleagues' 2015 trial found a rosemary oil preparation comparable to minoxidil 2% over six months. But that study was comparative rather than placebo-controlled and used a rosemary oil, not our serum, so it's promising ingredient evidence, not proof of our finished product. We won't overstate it.
Is ginger good for hair growth?
The evidence doesn't support that, and actually leans the other way: Miao and colleagues (2013) found ginger's 6-gingerol suppressed hair growth in lab and mouse models. Ginger is in our serum for the scalp environment and the warming, aromatic sensory experience of the ritual, not for growth. Any brand claiming ginger regrows hair is ignoring the strongest lab data.
Do spirulina and chlorella grow hair?
There's no persuasive human evidence that topical spirulina or chlorella grows or thickens hair. They're nutrient-dense algae included for antioxidant and scalp-environment support, and that's the honest reason they're in the blend. We're not going to claim a growth effect the studies don't show.
How is No. 02 different from No. 01?
No. 02 is plant-first, led by rosemary with a marine-algae blend and botanicals. No. 01 leads with five synthetic biomimetic peptides plus saw palmetto and rosemary, with a DHT-pathway rationale. They sit in the same morning slot; the choice is ingredient preference and, loosely, whether your thinning reads more androgenetic (lean No. 01) or you simply prefer botanicals (No. 02).
Is this serum a drug or clinically proven?
No. It's a cosmetic that supports the appearance of fuller-looking hair and a healthy-looking scalp through daily use; it doesn't regrow, treat, or prevent hair loss, and we don't make percentage or "clinically proven" claims for it. Cosmetic serums work with the hair cycle, not against the biology that sets the drug-class timeline.
How long before I can judge whether it's working?
The same timeline as any scalp serum: eight to twelve weeks of daily use for a first read, around month four for maximum effect. Hair grows on a multi-month cycle, and no topical shortcuts it. Photograph your part under consistent lighting once a month; memory is a poor judge of gradual change.
Our editorial approach. Unfurl content is researched and written by named authors and cross-checked against peer-reviewed literature (PubMed, Cochrane, NIH ODS) before publishing. We cite every claim inline. Articles are editorially reviewed, not medically reviewed, and nothing on this site is medical advice. Talk to a clinician before starting any supplement. These statements have not been evaluated by the FDA.
A friendly note to close: we're a hair and scalp care company, not a medical one. Everything here is for general education, not medical advice, and it can't diagnose a condition or take the place of a visit with someone who can examine you. If your hair or scalp has you worried, please talk to a doctor or a licensed clinician you trust.