Generally, compost can sit for a long time without any worry. It won't stink or rot when it’s properly taken care of by controlling the moisture levels. However, compost can lose potency over time. The nutrients leach, and the compost will turn finer and finer as the microorganisms get to work. Too much moisture can cause the compost to rot and grow fungi. And if your compost is in a pile and not in a bin, it could disappear altogether, becoming part of the soil.