By Jennifer Copley (Last Updated 8 March 2011)
Composting usually takes anywhere from a couple of months to a couple of years, depending on the effort you put into it and the materials used. Chopping or shredding materials and turning the pile regularly speeds the process significantly. If properly tended, composting should take 2-3 months, though letting the compost age for another couple of months is beneficial. If you don’t chop up the materials, it may take 4-8 months or more. Compost tumblers can reduce the processing time to a few weeks.
There are some materials that may take longer to break down in home composters, such as compostable plastics. Compostable plastics are made from organic materials (corn, potatoes, soy, etc.) that can decompose back into water, biomass, and carbon dioxide after composting. However, most home composting systems don’t produce enough heat to break these plastics down quickly, so the process may take a couple of months longer than with other compostable materials, and as long as 2 years for some compostable plastics. Commercial composters, which grind materials and generate more heat, can decompose these bioplastics more quickly.
Composting is complete when the material is crumbly and dark, with an earthy smell. You can remove completed compost from materials that are not yet broken down by sifting the material through wire mesh and then returning the partially decomposed items to the pile.