Independent reviews of natural and sustainable haircare
Updated 13 August 2026 · By Emma Hartley, Beauty Editor · 9 min read
Cornish Seaweed Bath Company Review 2026: Super Nutrient Haircare Set vs UpCircle's Haircare Duo
Cornish seaweed hair products have earned a loyal following, and The Cornish Seaweed Bath Company sits at the centre of it. But is its best-selling set still the strongest natural choice at £39.95? We spent four weeks washing with it alongside UpCircle's Shampoo + Conditioner Haircare Duo, comparing ingredients, performance, packaging and cost per wash. Here is what we found.
It washes just as well, costs £3.96 less, and it is the only set here whose green claims outside auditors have certified: B Corp, Certified Vegan, Cruelty Free International, Plastic Negative. The 100% natural Shampoo Crème and 98% natural Conditioner Crème come in fully recyclable glass jars with aluminium lids, and the concentrated formula needs only a blueberry-sized amount per wash. Read the full review ↓
Runner-up
The Cornish Seaweed Bath Co. Super Nutrient Haircare Set8.9/10
A genuinely well-made seaweed and herb set with outstanding customer feedback (4.8 stars from more than 10,000 reviews) and a generous 60-day returns window. It loses on price, certifications and packaging.
Our winner's brand has been featured in
How We Compared Them
We bought both sets at full price and alternated them over four weeks of washes, switching sets each wash day and keeping water temperature and routine the same. We scored five categories: ingredients, performance, packaging and sustainability, value, and customer feedback. Where we could not test something directly (long-term claims, for example), we relied on each brand's published information and the products' own review pages, and we say so in the text.
Cornish Seaweed Bath Company Review: The Super Nutrient Haircare Set
★★★★★4.8 (10,178 reviews)8.9/10
Best for: seaweed devotees who want a bigger bottle and a long returns window.
The Cornish Seaweed Bath Company has been making seaweed-based washes in west Cornwall since 2013 and has shipped over 300,000 orders, so this is no pop-up brand. The Super Nutrient Haircare Set pairs a 280ml shampoo with a 280ml conditioner, both built around organic seaweed (Fucus serratus) and herb extracts, with argan and oat kernel oils, panthenol, and a clary sage, rosemary and peppermint scent. The brand states the formula is 100% natural, free from silicones, SLS and parabens, and vegan-friendly.
In our four weeks with it, the set performed well. Hair felt soft after the first couple of washes and the herbal scent is pleasant without being overpowering. Customer feedback backs that up: the set holds 4.8 stars from 10,178 reviews, with owners describing thicker-feeling, glossier hair after a few weeks of use. The 60-day no-quibbles refund policy is the most generous returns window we have seen in this category, and delivery is free over £45.
The weaknesses are practical rather than fatal. At £39.95 it is the more expensive set here. The aluminium bottles are recyclable, but they come with plastic pump nozzles, and we could not find a refill scheme behind them. And while the brand's cruelty-free and vegan statements are clear, we could not find third-party certifications (B Corp, Vegan Society or Cruelty Free International marks) listed on the product page, so you are taking the brand's word for it.
Pros
100% natural formula (per the brand) with organic seaweed and herb extracts
Excellent customer feedback: 4.8 stars from 10,178 reviews
Generous 280ml bottles
60-day no-quibbles refund policy
Made in Britain (west Cornwall)
Cons
£39.95, the pricier set in this comparison
No third-party certifications listed; vegan and cruelty-free are self-declared
Aluminium bottles ship with plastic pump nozzles; no refill scheme that we could find
UpCircle Shampoo + Conditioner Haircare Duo Review
★★★★★4.6 (781 reviews)9.3/10
Best for: anyone who wants certified natural haircare that outlasts its size and costs less per month.
UpCircle is the London B Corp that built its name rescuing by-products (coffee grounds, fruit stones, orange peel) and turning them into skincare; it was backed on Dragons' Den in 2018 and its range now carries over 25,000 five-star reviews. The Shampoo + Conditioner Haircare Duo brings that same approach to hair: a 100% natural Shampoo Crème with coconut and rosemary oil, and a 98% natural Conditioner Crème with plant keratin and panthenol, in two 100ml frosted glass jars with aluminium lids. Both are sulphate-free, silicone-free and safe for coloured hair.
The format is the point. Call it concentration over dilution: most liquid shampoo is mostly water, so UpCircle makes its crème with 50% less water and states on the box that it delivers three times the washes of an equivalent liquid. You use a blueberry-sized amount, worked into a wet scalp. That is why a 100ml jar refuses to run out at the pace its size suggests, and why the most repeated line in the duo's reviews is some version of "a little goes a long way."
Over our four weeks, the shampoo lathered better than we expected from a sulphate-free crème and rinsed clean, leaving hair glossy rather than coated. The conditioner is light; fine hair stays lifted, though very dry or thick hair may want a slightly larger dose (a point one 4-star reviewer makes below). The rosemary and citrus oils give a fresh, spa-like scent that fades politely. It supercharges and nourishes hair for a glossy shine, is formulated to reduce breakage and strengthen strands, and promotes a healthy scalp; several long-term reviewers describe itchiness settling down within weeks.
Day-six curly hair, before and after one wash with the Shampoo Crème. Photo and quote: customer Eve, from UpCircle's gallery. Individual results may vary.
This is where the duo pulls away. UpCircle is a certified B Corp, Certified Vegan, Cruelty Free International approved and Plastic Negative, and the brand was a CEW UK Responsible Beauty finalist in 2026. The jars and lids are 100% recyclable, and a refill scheme means you do not have to bin the packaging at all. The formulas use bio-based, vegan ingredients only, including upcycled pink berries and orange peel wax.
At £35.99, the duo already saves 10% against buying the two jars separately (£39.99), and it is nearly £4 less than the Cornish set. Subscribe & Save cuts it a further 15% to £30.59 a delivery. If you want to test the waters first, the "Pamper + Gift" Kit gets you 12 sample sachets for £20 and includes a £20 gift card to put toward full sizes, and UpCircle's quiz builds a personalised routine at up to 30% off. Bundles save up to 30% too. UK delivery is free over £40, and there is a 14-day money-back guarantee.
Pros
100% natural shampoo, 98% natural conditioner, vegan ingredients only
Certified B Corp, Certified Vegan, Cruelty Free International, Plastic Negative
Concentrated crème: made with 50% less water for three times the washes (on-pack claim, echoed by reviewers)
100% recyclable glass jars with aluminium lids, plus a refill scheme
£35.99 (nearly £4 less than the Cornish set), or £30.59 with Subscribe & Save
Sulphate-free and safe for coloured hair
Cons
14-day money-back guarantee is short next to Cornish Seaweed's 60 days
Jars are less familiar in the shower than pump bottles
14-day money-back guarantee · Free UK delivery over £40 · Subscribe & Save 15%
Round by Round: Where Each Set Wins
Round 1 · Ingredients
Both lean natural, but UpCircle pairs its 100% natural shampoo with vegan-only, upcycled ingredients and puts third-party marks behind the claims. Cornish Seaweed's organic seaweed extracts are genuinely distinctive. Edge: UpCircle, narrowly.
Round 2 · Performance
Both washed well in our four weeks. Cornish Seaweed's liquid format feels more familiar; UpCircle's crème lathers surprisingly well and leaves more shine than we expected. Reviewers of both report softer, stronger-feeling hair. Edge: even.
Round 3 · Packaging and sustainability
Glass jars and aluminium lids that are 100% recyclable, a refill scheme, Plastic Negative certification and B Corp status, against recyclable aluminium bottles with plastic pumps. Edge: UpCircle, clearly.
Round 4 · Value
£35.99 vs £39.95 up front, and the gap widens with Subscribe & Save (£30.59) and UpCircle's bundle savings of up to 30%. The concentrated dose stretches each jar further than 100ml suggests. Edge: UpCircle.
Round 5 · Customer feedback and guarantee
Cornish Seaweed's 4.8 stars across 10,178 set reviews and 60-day refund window beat the duo's 4.6 stars from 781 reviews and 14-day guarantee. Edge: Cornish Seaweed Bath Co.
Tally: UpCircle takes three rounds, Cornish Seaweed one, one even.
The duo in its natural habitat, alongside UpCircle's wider haircare range: Scalp + Hair Oil, Hair Serum and comb.
What Haircare Duo Owners Say
★★★★★4.6 · 781 reviews· 92% would recommend
Barbara GVerified buyer
July 2026
Ok, I was doubtful…
"Ok, I was doubtful this was really going to 'work' but I hold my hands up! I'm 67 years old, have shoulder length naturally grey hair and it SHINES!"
Would recommend
Krista GVerified buyer
August 2026
Soft and shiny
"This haircare combo came to the rescue when perimenopause hit with a vengeance. It leaves my hair soft, smells amazing, and goes a very long way."
Would recommend
Carol TVerified buyer
August 2026
Hair feels clean and healthy for longer
"Have fine hair with highlights and after using both products hair looks cleaner and healthier for longer than usual. A little goes a long way."
Would recommend
Anne BVerified buyer
July 2026
Excellent product. You must try it.
"No more itchy scalp, clean shiny hair. Using ingredients that will otherwise be wasted. Brilliant."
Would recommend
Vicki TVerified buyer
July 2026
Really like the shampoo…
"Really like the shampoo, leaves my hair clean and fresh. Also like the conditioner but it seems to disappear into my hair so I end up using more than I'd like."
Would recommend
Julie WVerified buyer
July 2026
My favourites!
"Love the smell and texture, shampoo lathers well and cleans my hair brilliantly and conditioner leaves it silky and smooth. Only need a small amount so excellent value too."
Would recommend
Reviews from the product's verified-buyer review feed on upcirclebeauty.com. Individual results may vary.
What to Look For in a Natural Shampoo and Conditioner Set
Read the natural percentage, not the leaf on the label. "Natural" is unregulated; a stated figure (UpCircle prints 100% for its shampoo and 98% for its conditioner; Cornish Seaweed states 100%) is harder to fudge.
Check for third-party marks. B Corp, Vegan Society and Cruelty Free International certification mean an outside auditor agreed. Self-declared claims are not worthless, but they are weaker.
Sulphate-free matters for coloured hair. Both sets here qualify.
Think in washes, not millilitres. A 280ml bottle you pump three times can empty faster than a 100ml concentrate you dose with a fingertip.
Packaging is part of the price. Glass and aluminium recycle indefinitely; plastic pumps often cannot be recycled kerbside.
Frequently Asked Questions
Is The Cornish Seaweed Bath Company a legitimate brand?
Yes. The Cornish Seaweed Bath Company has operated from west Cornwall since 2013, has delivered over 300,000 orders, and its Super Nutrient Haircare Set holds 4.8 stars from 10,178 reviews. Our verdict is not that it is bad; it is that UpCircle's duo gives you more for less.
What do Cornwall seaweed bath company reviews say about the haircare set?
Owners consistently praise softness, shine and the herbal scent, with several reporting thicker-feeling hair after a few weeks. Criticisms are rarer and usually mention price or personal scent preference.
Is the hair care Cornish Seaweed Bath Co. sells worth £39.95?
If organic seaweed is what you want, yes, and the 60-day refund policy protects the experiment. Purely on value, UpCircle's £35.99 duo undercuts it while carrying certifications the Cornish set does not list.
How is UpCircle's Haircare Duo different from cornish seaweed hair products?
Three ways: format (concentrated crème rather than liquid), credentials (B Corp, Certified Vegan, Cruelty Free International, Plastic Negative) and packaging (100% recyclable glass jars with aluminium lids plus a refill scheme).
Which set is better for an itchy or flaky scalp?
Both brands formulate for scalp comfort. UpCircle's duo promotes a healthy scalp, and duo reviewers with sensitive scalps describe itchiness settling after switching. Individual results vary; patch-test if your scalp is reactive.
Is UpCircle's shampoo really 100% natural?
Yes: the Shampoo Crème is 100% natural (the box says so), and the Conditioner Crème is 98% natural. Both are sulphate-free, silicone-free and made with vegan ingredients only.
How long does a 100ml jar actually last?
UpCircle states the crème is made with 50% less water and delivers three times the washes of an equivalent liquid; the recommended dose is blueberry-sized. "A little goes a long way" is the most repeated phrase in the duo's reviews.
Can I try UpCircle before buying the full duo?
Yes, two ways: the £20 "Pamper + Gift" Kit (12 sample sachets plus a £20 gift card toward full sizes) or the quiz, which builds a personalised routine at up to 30% off.
What are the returns policies?
UpCircle offers a 14-day money-back guarantee from delivery. The Cornish Seaweed Bath Co. offers 60-day refunds; that longer window is a genuine point in its favour.
Do these work on coloured hair?
Yes. UpCircle's duo is sulphate-free and safe for colour-treated hair, and Cornish Seaweed states its set suits all hair colours and types.
The Bottom Line
After four weeks with both sets, the UpCircle Shampoo + Conditioner Haircare Duo is the one we would buy again. It matches the Super Nutrient Haircare Set Cornish Seaweed Bath Co. is best known for on natural credentials, then beats it on price (£35.99 vs £39.95), on certifications (B Corp, Certified Vegan, Cruelty Free International, Plastic Negative) and on packaging (100% recyclable glass and aluminium, with refills). If you want the bigger bottles and the longer returns window, the Cornish set remains a respectable runner-up. For most people, the duo is the smarter buy.
