can you compost wool sweaters?
Yes, but only if the tag reads 100% wool, cashmere, or alpaca — cut it up, soak it, and plan on a year or more.
breaks down in 1–5 years; shredding and soaking speed it up
C:N ≈ 12:1
which bins can take it?
- hot pile yes
- cold pile caution
- worm bin no
- bokashi no
- tumbler no
- curbside no
- cold pile: Works on a multi-year clock; keep pieces small, deep, and damp.
- curbside: Sweaters are textiles — not accepted in curbside organics.
why?
Sweater wool is keratin held together by cystine disulfide bonds, which only specialized keratin-eating fungi and bacteria can cleave — and they colonize slowly at backyard pile temperatures. A dense knit compounds the delay by shedding water. That combination is why an intact sweater can sit in a cold pile for years while shredded, soaked pieces disappear in one or two.
how to prep it
- Check the tag for 100% animal fiber
- Remove buttons, zippers, shoulder pads, and labels
- Cut into strips or small squares
- Soak pieces overnight — lanolin repels water
watch out for
- Machine-washable 'superwash' wool wears a polymer film that defeats the microbes along with the felting.
- Wool-acrylic and wool-nylon blends dominate the sweater rack; the synthetic share persists as loose plastic knit.
what to do instead
Wearable sweaters should be donated, and blends go to textile recycling; felted scraps also make excellent weed-mat material under mulch.
often confused with
- Acrylic sweaters — The dominant budget sweater fiber — identical look, zero compostability, and it pills into microplastic fuzz.
quick answers
Can I use an old wool sweater as garden mulch?
Yes — lay it flat under wood chips as a weed barrier that waters through and feeds the soil as it rots over a few seasons. Many gardeners prefer this to pile composting wool.
Do cashmere, alpaca, and mohair compost like wool?
All of them — every animal hair fiber is keratin and follows the same slow, nitrogen-rich decomposition path as sheep's wool.