can you compost metal?
No — no metal decomposes in compost; even thin steel takes decades to corrode, and zinc- or lead-bearing pieces leach into your soil.
which bins can take it?
- hot pile no
- cold pile no
- worm bin no
- bokashi no
- tumbler no
- curbside no
why?
Composting is biology, and metals sit outside its chemistry — microbes can't oxidize iron, copper, or zinc for energy the way they burn carbon compounds. Corrosion is the only exit, and it's slow and dirty: galvanized coatings shed zinc, old solder and some alloys carry lead, and copper is directly toxic to the fungi and worms doing the pile's work.
what to do instead
Cans go in curbside recycling; anything bigger — pipe, wire, hardware, broken tools — is welcome at scrap-metal yards, which often pay by the pound. Metal is too recoverable to bury in a pile or send to a landfill.
quick answers
Do rusty nails add iron my plants can use?
That's a durable myth — rust is iron oxide, a form plants can't absorb. Yellowing from iron deficiency is almost always a soil-pH problem, fixed with chelated iron or by lowering the pH, never by burying hardware.
There are screws in my finished compost — is it ruined?
Not at all. Sweep a magnet over the pile as you screen it and the steel jumps right out; the compost itself is unaffected by a brief stay alongside a few fasteners.