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What is PLA? The plastic behind most "compostable" packaging

September 27, 20224 min read

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Chances are you have picked up a straw, cup or fork labeled "100% compostable," felt good about it, and moved on with your day. Most people never read the fine print, and why would they? The trouble is that the fine print is where the real story lives. Most of those items are made from PLA, and most of them never get composted. We first wrote this in 2022 and have updated it with what has changed since.

What PLA is

PLA stands for polylactic acid. It is a plastic made by fermenting plant sugars into lactic acid and then linking that acid into a resin. In plain terms, it is a plant-based material that looks, feels and performs much like conventional plastic. That is exactly why it became the default for compostable cups, straws and cutlery.

Where a material comes from does not tell you where it goes after use, though. Being plant-based and being able to compost in real life are two different things.

What "compostable" means on a PLA label

Composting is a great process. Done right, it turns organic matter into a soil amendment and keeps food scraps out of landfills. The question is whether the item with the compostable label ever reaches a composting process that can handle it.

PLA is certified for industrial composting, not home composting. Michigan State University packaging researchers note that it only breaks down meaningfully above roughly 58°C (about 136°F), and that it fails home composting tests.

Three things have to go right for PLA to compost

It has to be separated. PLA must be kept apart from regular trash and conventional plastic. That means a dedicated bin, clear signage, and guests who use it correctly.
It has to reach a facility that accepts it. Not every composting facility takes compostable packaging, and acceptance varies by item type, according to BioCycle's 2023 national survey. Many facilities sort by sight, and PLA looks a lot like conventional plastic.
It has to get hot enough for long enough. The facility has to hold the high temperatures PLA needs for the full process.

If any one of those steps fails, the PLA item is just trash. In practice, most of it ends up in a landfill, where it is not composted at all.

Picture it from the restaurant side

Say you own a restaurant and want to move away from single-use plastic. You search for eco-friendly packaging, find a page full of compostable options, and order the one that fits your budget. It arrives in a few days and you get back to what earns your living: the food and your guests. At no point did anyone explain what has to happen for those products to actually compost. That is not your fault. It is a gap in how these products are sold.

Why this is a greenwashing problem

Greenwashing means giving a misleading impression that a product is better for the environment than it really is. A compostable label on an item that has nowhere to compost fits that description. Federal guidance agrees: the FTC's Green Guides say marketers should clearly and prominently qualify compostable claims when composting facilities are not available to a substantial majority of the people where the item is sold.

California has gone further. Under its compostable labeling law (Public Resources Code section 42357), anything labeled "home compostable" must hold OK compost HOME certification, and from June 30, 2027, products labeled compostable there must also qualify as an allowable input under the USDA National Organic Program.

What you can do about it

If you run a business

Be wary of compostable claims and ask your supplier which certification backs each one.
If you choose industrial compostable items, set up real composting: separate bins, a hauler that accepts them, and staff who know the system.
If your guests have no access to industrial composting, look for products certified home compostable (OK compost HOME).

If you are a guest

When you see a business using compostable products, ask them how they compost. Most are not aware of what it takes, and a friendly question is often the start of a better system.

A different approach: certified home compostable PHA

We think foodservice deserves a better answer than PLA, so we make CompostZero™, our own PHA material, made through fermentation from renewable feedstocks. PlantSwitch products are certified home compostable, with certifications from TÜV Austria (OK compost HOME), BPI and DIN CERTCO across the line, and they are FDA compliant for food contact. CompostZero™ stands for No Forever Microplastics.

Want the longer comparison? Read why PLA isn't actually compostable and our PHA vs. PLA guide.