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Your hair has two problems. Most products only solve one.

Shedding starts at the scalp. Thinning shows through the lengths. The Stronger Strands System is the only complete 4-product routine that addresses both -- with clinically tested results at every step, and no harsh drugs.

93% experienced less shedding*
82% saw increased thickness on the full system*/**
97% saw overall improvement*
Get the Stronger Strands System
Woman applying ProGRO Density+ serum dropper to scalp
★★★★★  4.7 · 4,700+ reviews
✓ Clinically Tested
✓ Drug-Free Formula
✓ Dermatologist Tested
✓ 90-Day Guarantee

Four products. Every step covered.

Most hair growth approaches stop at the serum. The Stronger Strands System pairs a clinically tested scalp serum with a Biotin haircare routine designed to support it -- so each product works with the others, not in spite of them.

ProGRO Density+ Scalp & Hair Serum
Daily Scalp Serum
ProGRO Density+ Scalp & Hair Serum
VitaGRO Complex: Redensyl 3%, ALGAKTIV Densidyl, Eterwell HAIR, BeauPlex VH. Apply daily to dry scalp, massage 60 seconds, no rinse.
Biotin & Superfruit Volumizing Shampoo
Cleanse
Biotin & Superfruit Shampoo
Sulfate-free, silicone-free cleanse with Biotin B7 and 5X Vitamin Complex. Creates the clean scalp environment the serum needs.
Biotin & Superfruit Volumizing Conditioner
Condition
Biotin & Superfruit Conditioner
Vegan collagen, elderberry, and plum oil replenish moisture without silicones that block scalp absorption.
Oh My Growth Booster Spray
Between Washes
Oh My Growth Booster
Leave-in Biotin B7 booster. Keeps the routine going between wash days so every day counts, not just wash days.

Why a single serum often falls short

  • x A scalp serum applied after sulfate-heavy shampoo fights residue and buildup from the start
  • x Silicone-heavy conditioners coat the scalp and reduce how well topical ingredients absorb
  • x One product targets one pathway. Thinning hair typically involves more than one.
  • x Without supporting haircare, results can plateau before they become visible -- and people quit too early

How the system changes the outcome

  • + Sulfate-free, silicone-free cleanse and condition prepares the scalp to receive the serum each time
  • + ProGRO VitaGRO Complex targets four pathways: Redensyl 3%, ALGAKTIV Densidyl, Eterwell HAIR, BeauPlex VH
  • + Biotin haircare helps support hair health between serum applications -- every day, not just wash days
  • + Both formulas clinically tested independently. Both studied on the combined system.
82% saw increased thickness on the full system in independent third-party studies*/**

Starting at $1.67/day on subscribe · See the offer →

5 reasons the system works where a single serum stalls

1
A clean scalp environment is not optional

The ProGRO serum performs best on a scalp free of sulfate residue and silicone buildup. The Biotin & Superfruit shampoo and conditioner are formulated without either -- so your scalp is prepared to receive the serum, not working against it.

2
Four pathways are better than one

VitaGRO Complex combines Redensyl 3%, ALGAKTIV Densidyl, Eterwell HAIR, and BeauPlex VH -- each targeting a different aspect of scalp and follicle health. Plus rosemary, caffeine, and saw palmetto. This is a multi-pathway approach, not a single active ingredient.

97% saw overall improvement in a 44-day third-party study, 30 participants*
3
The haircare half has its own clinical data

The Biotin & Superfruit routine was studied separately from the serum. 96% of participants said they would switch to this system and 82% noticed increased thickness. These are independent results for the wash half of your routine -- not borrowed serum claims.

96% said they would switch to this system in a 28-day third-party study, 33 participants**
4
No harsh drugs. No prescriptions.

No minoxidil. No finasteride. The Stronger Strands System is drug-free, dermatologist tested, and designed for consistent daily use. If you have seen ads for prescription hair solutions and want results without the drug side, this is the clean-science alternative.

5
90 days to decide whether it worked

Visible improvement from the serum typically begins around 6 weeks with consistent daily use.* We give you 90. If you are not satisfied after that, return the product. No language about "undamaged packaging" or returns that require a phone call -- that is the actual policy.

Most people quit right before it works.

Visible improvement from the serum typically begins around 6 weeks.* Here is what the first three months actually look like.

Week 2 – Month 1
Less hair in the drain.

Shedding is usually the first thing people notice changing. It is not dramatic -- you just stop dreading the shower. 93% experienced less shedding in the 44-day study.*

Month 2
Your part looks a little different.

You keep checking. The density at your scalp is starting to feel more like it used to. Hair texture improves too -- the Biotin routine is doing its part here.

Month 3+
You stop counting the drain.

Not because you forgot -- because you stopped worrying about it. 83% said hair looked fuller with more volume by the end of the study.*

If you are not satisfied after 90 days of consistent daily use, return the product. That is the guarantee. → Starting at $1.67/day on subscribe.

The numbers behind the system

Two independent studies. Two separate formulas. Both tested by third-party researchers.

ProGRO Density+ -- 44-day study, 30 participants*
97% saw overall improvement
93% experienced less shedding
90% noticed new growth
83% said hair looked fuller with more volume
76% saw less breakage
*Based on a 44-day third-party consumer perception study, 30 participants, April 2026. Results may vary. Visible improvement beginning at 6 weeks.
Biotin & Superfruit -- 28-day study, 33 participants**
96% would switch to this system
91% said hair felt healthier
85% saw softer, shinier hair
85% said hair looked less damaged
82% noticed increased thickness
**Based on a 28-day third-party clinical study, 33 participants, August 2025. Results may vary.

See it on a real scalp.

Kitty documented her part width starting at week 2. These are her actual photos.

Kitty's scalp before ProGRO Density+ BEFORE
Kitty's scalp after ProGRO Density+ AFTER

Real Results

Before ProGRO Density+ BEFORE
After ProGRO Density+ AFTER
★★★★★

"It absorbs quickly and doesn't interfere with my hairstyle or make my curls look oily. My scalp felt calm and balanced throughout the time I was using it."

Kitty Y. (@kittyluvkitkat) · Verified Buyer · Visible improvement starting at week 6. Individual results may vary.

UGC video — swap with Allie's top-performing clip

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★★★★★

"Love this product! Just a nickel-size dollop leaves my hair shiny and so healthy looking, plus there’s less hair in the sink when I comb it out."

Linda · Verified Buyer · Biotin Haircare Essentials

★★★★★

"I've been using the SoapBox ProGRO Density+ Hair & Scalp Serum for a little while and I'm already seeing a difference in how my hair looks and feels."

Yarelyn C. · Verified Buyer · ProGRO Density+

★★★★★

"As someone with PCOS, I do experience hair fall and have fine hair on my scalp. This has made a real difference in how full my hair looks."

Khushmeet A. · Verified Buyer · ProGRO Density+

4.7 stars · 4,700+ verified reviews · Individual results may vary.

The complete routine vs. the single-product approach

Most competitors give you one thing. Here is what the full system delivers that a serum alone cannot.

Feature Stronger Strands System Serum-only approach Prescription minoxidil
Complete multi-product routine ✓ 4 products ✕ 1 product ✕ 1 product
Clinically tested serum ✓ 44-day study Varies by brand ✓ Drug-approved
Clinically tested haircare ✓ 28-day study ✕ ✕
Drug-free formula ✓ ✓ ✕
Sulfate-free + silicone-free haircare ✓ Included Requires separate purchase ✕
90-day satisfaction guarantee ✓ Varies by brand ✕
Mission-driven brand (gives back) ✓ 60M+ bars donated ✕ ✕
Stronger Strands System -- four products on warm beige background

Stronger Strands System

ProGRO Density+ Serum + Biotin & Superfruit 3-Piece Haircare

Supply
$69.99 $79.99

per month, cancel anytime • free shipping on orders over $50

🎁
Free ProGRO Scalp Applicator ($14.99 value) Included with every system order
✓ ProGRO Density+ Scalp & Hair Serum (1 fl oz) $54.99 value
✓ Biotin Volumizing Shampoo (16 oz) $10.99 value
✓ Biotin Volumizing Conditioner (16 oz) $10.99 value
✓ Oh My Growth Booster $10.99 value
✓ Free ProGRO Scalp Applicator $14.99 value
✓ Free Shipping (orders over $50) Included
✓ 90-Day Satisfaction Guarantee Included

Subscribe and save -- cancel anytime

90 DAYS

90-Day Satisfaction Guarantee

We ask for 90 days of consistent daily use before you decide whether the system worked. Visible improvement from the serum typically begins around 6 weeks -- but we give you 90. If you are not satisfied, return the product for a refund. That is the policy.

Questions we get a lot

In our 44-day third-party study, visible improvement from the serum was noted beginning at 6 weeks of consistent daily use.* Reduced shedding may become noticeable earlier for some. The Biotin haircare routine can make hair feel healthier within the first few washes -- that is a different result from the serum, and they support each other over time. Results vary by individual.
ProGRO Density+ is applied to the scalp, not the lengths. It is lightweight, no-rinse, and absorbs without leaving residue when applied correctly. Apply to a dry or towel-dried scalp, massage for 60 seconds, and leave it. If you find it heavy, try a smaller amount or apply it before bed.
Yes. The Biotin & Superfruit shampoo and conditioner are color-safe, sulfate-free, and silicone-free. The ProGRO serum is applied to the scalp rather than the lengths, so it does not affect color. Both formulas are hypoallergenic and vegan.
No. The Stronger Strands System is entirely drug-free. It contains no minoxidil, no finasteride, and no prescription ingredients. The ProGRO serum uses VitaGRO Complex -- Redensyl 3%, ALGAKTIV Densidyl, Eterwell HAIR, and BeauPlex VH -- which are cosmetic-grade scalp ingredients studied for scalp and hair health, not drugs. The system is dermatologist tested and hypoallergenic.
If you use the system consistently for up to 90 days and are not satisfied with the results, you can return the product for a refund. Because visible results from the serum typically begin around 6 weeks, we want you to have enough time to see whether the system is working for you. Contact our support team to start a return.