The world's trusted guide to sustainable and ethical fashion

The world's trusted guide to sustainable and ethical fashion

How to Compost Your Clothes

Image: Freitag’s compostable jeans

Statistics around garment waste are truly staggering, and images of landfills of discarded clothes have been seared into our minds. Each year, 400 million pounds of clothing ends up in New York City’s landfill sites alone — equivalent to the weight of nearly 120,000 mid-sized cars. According to the Dutch retailer LABFRESH, the UK produces 227,579 tons of textile waste a year, which further breaks down to 1.7 kilograms per person per year sent to the incinerator.

So, what’s a good end-of-life solution for your clothes if you don’t want them to end up in a landfill? If they’re still in good condition, you can donate them to a charity shop, sell them to a thrift store, or participate in a clothing swap with your friends. If the garment is slightly damaged, you can consider repairing it. But there will come a time when the fabric is so worn out that repair or reuse is not an option anymore. 

There has been a buzz around composting clothes — biodegradable fabrics seem to have become the next big thing in sustainable fashion. The question is, how do we know if an article of clothing is suitable for your backyard compost, and if so, how should we do it? 

We spoke to the experts to find some answers.

What fabrics are truly biodegradable?

The first question to ask is if the fabric itself is compostable. 

A simple rule of thumb is that 100% natural fibers can decompose within our lifetime, while most synthetic fibers can’t. Natural fibers include pure cotton, linen, hemp, silk, wool, cashmere, and jute. Rayon, bamboo rayon, and lyocell, which are semi-synthetic cellulosic fabrics, biodegrade too. In fact, according to a study, rayon biodegrades even faster than cotton, while Tencel lyocell is slower. 

Synthetic fibers, which include polyester, spandex, acrylic yarn, and nylon, can take decades to hundreds of years to break down in the soil, so they’re definitely not suitable for even municipal compost collection. 

“Fabric from any small-scale farm yarn business will usually be compostable. So if you buy yarn directly from somebody’s farm, and they say it’s a hundred percent their sheep’s wool, or a hundred percent their own grown cotton, it’s a high likelihood that that is going to work well in your compost pile,” says Rebecca Burgess, founder of Fibershed, a non-profit based in Marin County, California that supports economic development of natural fiber and dye systems.

But as you may have guessed, it’s not that simple. There are several factors that can make a piece of clothing non-biodegradable, even if the primary fabric itself is natural. 

Natural Fiber, Synthetic Finish

While 100% organic cotton itself will biodegrade, you probably can’t stick your old cotton tee into your home compost. Here’s why:

Fiber Blends

You’ve probably seen brands advertising their clothing as being made of 95% organic cotton, 5% spandex, or another synthetic. It’s common for fibers to be blended with synthetics like polyester or elastane to improve the durability or elasticity of the material, and this is especially true when it comes to athletic wear. 

“We certainly won’t be able to compost poly acrylic fiber blends, and unfortunately this is a common material used in fast fashion. It’s a complete no-go. Wool nylon blends are a no-go too,” says Burgess.

And it’s rarely possible to separate out the synthetic component and then compost the remaining organic material. “The fiber mix is usually done at the yarn stage,” says Paul Foulkes-Arellano, founder of Circuthon, a management consultancy that helps businesses transition to circularity. This means that the synthetic fibers are spun into the organic material making them tightly wound together and almost impossible to separate, especially at home. 

Synthetic Dyes 

Many brands opt for synthetic dyes since they’re cheaper than their natural counterparts. And as many things synthetic go, some of these chemicals can be toxic and potentially carcinogenic. So while it may not prevent a fabric from composting, it’s possible that the chemicals will leak out and contaminate the environment.  

“Dyes, like synthetic indigo in jeans, will mean the toxins are left in the ground when the jeans are composted,” explains Foulkes-Arellano. 

And this is where it starts to get trickier. While a fabric label will tell you what fibers are used to make the garment, the dye ingredients are typically not mentioned. For that reason, unless clearly stated otherwise, there is no way to know if clothing has a problematic dye involved even though Europe and most U.S. states have bans on some dyes in place. 

“To be safe, I try to work with clothing that’s either undyed or very clearly marked naturally dyed,” says Burgess.

Look out for the Cradle to Cradle certification, which will tell you if the product is free of toxic chemical contamination. Some brands that are trying to incorporate natural dyes into their products include Older Brother, Hara the Label, Harvest and Mill, California Cloth Foundry, Indigo Luna, and Gaia Conceptions

Fabric Finishes

Fabrics are often coated in chemical “finishes” to improve the look or performance of the final garment. These finishes can make the fabric crease-, stain-, or water-resistant, anti-microbial, or anti-static. Like chemical dyes, synthetic finishes, including formaldehyde and silica gel, can be toxic and can contaminate your compost too. 

They can also prevent the material from biodegrading. “Materials like wool typically have a polymer coating to increase the strength of the fabric, which are wedded into the threads and yarns. This stops the wool from biodegrading, because the coating protects the cellulosic bit from the microbes that break it down,” says Foulkes-Arellano. “The way that composting works is the plant material, whether it’s cotton, linen, hemp, nettle, or castor bean oil, is being eaten by tiny microbes. Now imagine there’s a massive big plastic layer coating it. The microbes don’t eat plastic. It’s like wrapping a sandwich in plastic, you can’t get to the center.” 

Unfortunately, the ingredients used in the fabric finishes aren’t usually mentioned in labels either. Typically, garments made locally and by traditional artisans with plant and mineral dyes should be safe to compost. And again, a compost-safe certification by Cradle to Cradle is good to look out for. 

Trims, Threads, and Embellishments

Zippers, labels, and buttons are typically made from plastic, metal, or other non-compostable elements. Look out for brands that are using compostable buttons made of materials like wood, coconut shell, or corozo (vegetable ivory). Avoid sequins or glitter, which are usually made of plastics. 

Sewing threads often contain synthetics to improve sturdiness. According to a report by Patagonia, these threads are typically made of polyester or cotton wrapped around a polyester core. These threads will not decompose in your backyard. You could technically sift through your bin a couple of months later, when everything else has rotted down around it, and pluck out the strings left in there. But we would steer clear of this for two reasons. One, sifting around that rotten plant matter won’t be fun. And two, as with the finishes and dyes, if you’re not sure of what exactly has gone into the threads, you don’t want it to potentially contaminate your soil. 

“That’s what makes three dimensionaly knitted garments that don’t use polyacrylic thread such a great option for composting at the end of their life,” says Burgess. That’s because knitted garments don’t always use threads or trims and can be a mono-material. “But we’re not really designing clothes for this purpose and so it is not easy to find those clothes at the moment,” she admits.  

Some brands are using sewing threads in their garments that biodegrade. For example, this dress from Freitag is completely compostable. It uses a special sewing thread and ivory nut buttons. According to the brand, it’ll decompose completely in your compost in a couple of months. 

So, assuming you’ve got a well-loved artisanal piece of clothing that ticks all the above boxes and is unsalvageable…

How do you compost old clothing?

Step 1: Read the labels. Make sure that the garment is made entirely from organic fibers. Only clothes that are naturally-dyed, made locally or by traditional artisans, or certified in some way as compostable should be included. If you’re on the lookout for brands that make compostable clothes, check out our list here.    

Step 2: Make sure the garment isn’t stained with an item from the do-not-compost list. This includes cooking or engine oils, paints, or other toxins. If it can be removed easily by washing or snipping out the offending piece, great. If not, keep it out of your compost pile. 

Step 3: Remove all trims made of synthetic materials, like buttons, zippers, or labels. Cut out any hems, collars, or cuffs that are made from non-biodegradable materials. 

Step 4: Cut up the fabric into small pieces. This will help the material break down, or rot, faster. 

Step 5: Toss the fabric pieces into your compost bin. 

Make sure your compost bin has a healthy balance of “greens” and “browns.” Compost “greens” consist of fresh or wet waste like fruit and veggie peels, coffee grounds, and eggshells. These are rich in nitrogen and decompose faster. “Browns” include dry or woody plant materials like paper, cardboard, dried leaves and, in this case, your old clothing! These are rich in carbon and take longer to break down. 

While it is possible to compost clothes, most retailers are not quite there yet. The industry has a long way to go, particularly when it comes to transparency on clothing ingredients. That’s too bad, because compostable clothing could divert millions of pounds of old clothes from landfills every year, and completely revolutionize the fashion industry. 

But there is one upside: It’s yet another reason to buy natural fashion from local artisans! 

Correction: We originally included rayon in the list of synthetic fibers. It’s a man-made cellulosic fiber. We included bamboo in the list of natural fibers; most bamboo fabric is a semi-synthetic bamboo rayon. 

Piles of used clothing in a warehouse

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