can you compost pla cups?
Only at a commercial composting facility — PLA needs sustained 130–140°F to break down, and backyard piles leave the cup looking new.
breaks down in 45–90 days at an industrial facility; effectively indefinite in home piles
which bins can take it?
- hot pile no
- cold pile no
- worm bin no
- bokashi no
- tumbler no
- curbside caution
- curbside: Accepted only where your program explicitly lists PLA serviceware — a growing number have stopped taking it.
why?
Polylactic acid stays rigid and inert until it passes its glass-transition temperature around 140°F, when the polymer softens enough for moisture to cleave its chains into lactic acid that microbes finally eat. Industrial windrows hold that heat for weeks; a home pile touches it briefly at the core, if at all. Burial trials routinely recover PLA cups essentially unchanged after a year in soil or slow compost.
how to prep it
- Confirm the BPI mark or 'commercially compostable only' print on the cup
- Keep PLA out of the recycling bin — it ruins PET bales
watch out for
- PLA is nearly indistinguishable from PET #1 plastic by eye, and one PLA cup can downgrade a whole bale of PET recycling.
- Several large composters have dropped PLA serviceware because half-degraded shards kept showing up in screened compost.
often confused with
- Clear PET Cups (#1 Plastic) — Flip it over: PET shows a #1 recycling code and belongs in recycling; PLA shows a #7 or a leaf/BPI logo and never goes in the recycling bin.
quick answers
Can I just bury a PLA cup in the garden?
You'll dig up a dirty cup years later. Soil never approaches the sustained heat PLA requires, and buried plastic-like litter attracts no decomposers — burial is storage, not disposal.