Is Cotton Biodegradable? What Parents Should Know About Sustainable Fabrics

If you’ve ever wondered what happens to your child’s outgrown clothes after they leave your home (and sadly, if or rather when they end up in a landfill), you’re not alone. The short answer: yes, cotton is biodegradable,  but not all cotton fabrics decompose equally.
Some break down within months, returning safely to the earth. Others linger in landfills for years, releasing toxins along the way.

Let’s unpack what makes the difference between those two and ultimately how choosing the right kind of cotton helps protect both your child and the planet.

What Does “Biodegradable” Really Mean in Clothing?

To put it succinctly, when something is biodegradable, it means nature knows what to do with it. Microorganisms,  bacteria, fungi, and even worms can break it down into simple, non-toxic elements like carbon dioxide, water, and organic matter.

Natural fibers such as cotton, linen, and hemp decompose easily because they come from plants. Synthetic ones,  polyester, nylon, and acrylic,  are made from petroleum, so they don’t. Instead of disappearing, they fragment into microplastics that pollute waterways and even end up in our food and in our bodies.

Here’s an image that helps:

• A 100% cotton onesie can decompose in a compost heap within a few months.
  

• A polyester onesie could still be intact when your great-grandkids are alive.
  
  

Is Cotton Biodegradable? (The Short Answer)

Absolutely,  pure cotton fibers are 100% biodegradable.

Cotton is made of cellulose, a natural compound that microbes love to eat. Under warm, moist, oxygen-rich conditions (like in a compost pile), cotton can break down in as little as one to five months.

But here’s the catch: that’s true only when the fabric is untreated.
But the annoying thing is, very little conventional cotton is untreated. Conventional cotton clothing often comes with coatings, dyes, and chemical finishes that make it wrinkle-free, stain-resistant, or “soft to the touch.” Those same chemicals make it a heck of a lot harder for the fabric to break down,  sometimes turning a biodegradable fiber into one that behaves more like plastic.

What Affects Cotton’s Ability to Decompose

Cotton’s biodegradability depends on what’s added to it after harvesting.

1. Blended fabrics. A cotton-polyester tee won’t biodegrade because the polyester part won’t. One plastic thread is enough to compromise the entire garment.
   

2. Chemical finishes. Anti-wrinkle, flame-resistant, or water-repellent coatings slow or even block microbial breakdown.
   

3. Synthetic dyes and prints. Many fast-fashion items use azo dyes or plastic-based inks that interfere with natural decomposition.
   

It’s for this reason (not to mention because of many others) that at Treehouse Kids, we avoid every one of these pitfalls.
We choose fabrics left natural and untreated so that when their time comes, they return to the earth,  safely and cleanly.

Explore our organic cotton clothes for kids →

Organic Cotton vs. Conventional Cotton: Why It Matters

All cotton starts out natural, but not all cotton stays that way.

Organic cotton is grown and processed without pesticides, formaldehyde, or toxic finishes. That means it doesn’t just biodegrade faster,  it biodegrades cleaner. No harmful residues, no hidden plastics, no chemical afterlife.

In contrast, conventional cotton farming relies heavily on synthetic fertilizers and pesticides, and the finishing process often adds coatings that linger long after the garment’s “lifetime.”

What that means for us is that every piece we make is crafted from GOTS-certified organic cotton or linen made from OEKO-TEX® Standard 100 certified fabric.

GOTS (Global Organic Textile Standard) focuses on how the cotton is grown and processed — ensuring it’s organically farmed, ethically produced, and free from toxic inputs throughout the supply chain.

OEKO-TEX® Standard 100, on the other hand, is a product safety certification. It means the linen fabric itself has been independently tested and verified to be free from over 350 harmful substances, including formaldehyde, heavy metals, carcinogenic dyes, and endocrine disruptors.

Fewer chemicals mean:

• Faster and more complete biodegradation
  

• Softer, safer fabric against your child’s skin
  

• Cleaner air, soil, and water once it’s gone
  

Want to understand this difference in detail?

👉 Read more: Organic cotton vs. conventional cotton

How to Dispose of Cotton Clothing Responsibly

Even the most sustainable fabric can create waste if it’s tossed mindlessly. Here’s how to make sure your little one’s outgrown clothes end up in the right place:

1. Reuse and repurpose. Turn soft cotton tees into reusable wipes, cleaning cloths, or even kids’ art supplies.
   

2. Donate or swap. If the garment’s still wearable, pass it on. Local parenting groups, community swaps, and donation bins extend their life.
   

3. Recycle textiles. Many cities and brands now collect old cotton clothing for fiber recycling or insulation projects.
   

4. Compost (if pure). Small scraps of undyed, untreated organic cotton can safely go in a home compost. Just cut them into smaller pieces to speed things up.
   

Avoid composting anything blended with polyester, elastane, or synthetic finishes; those belong in textile recycling instead.

Shop our organic cotton baby clothes →

Why Biodegradability Matters for Kids’ Clothing

Every piece of clothing eventually reaches its end. The question is: what happens next?

For parents, biodegradable fabrics mean two things:

1. Less waste in landfills,  your child’s outgrown clothes can safely return to nature instead of sitting around for centuries.
   

2. Less exposure to toxins,  organic cotton doesn’t rely on chemical finishes or microplastics that can irritate young skin or pollute your home’s dust.
   

Treehouse Kids was built around this very idea: that what touches your child’s skin should never harm them,  or the earth they’ll inherit.
It’s also exactly why we choose certified organic cotton, gentle natural dyes, flat seams for comfort, and thoughtful design that lasts long enough to pass down, then biodegrades without a trace.

Explore Our Certified Organic Cotton Collections

Browse the full range of organic essentials designed for comfort, longevity, and safety:

• Baby onesies and sleepers
  

• Kids’ pajamas and underwear
  

• Everyday tees and linen pants
  

Each piece is crafted from breathable, toxin-free cotton that keeps children comfortable today and the planet healthy tomorrow.

Organic Cotton Pajamas

Kids' Organic Cotton Underwear

Organic Cotton Baby Sleepers

Short-sleeved bodysuits

Long-sleeved bodysuits

Kids' Organic Cotton T-Shirts

Kids' Organic Cotton Pants