When is Compost Ready to Use?
Compost is ready to use after 1 to 12 months, depending on the size of the materials placed in the compost system, the degree of management, and the intended use. Compost that will be used as a top dressing or mulch can be applied after the least amount of time. Compost that will be used for growing plants in containers must be thoroughly composted.
There are many terms for compost that is ready to use. Some call it "stable," others call it "finished"; still others call it "mature".
Signs that your compost is ready to use:
- The pile has shrunk significantly, up to one-half its original volume;
- The original organic materials that you put in are no longer recognizable for what they were;
- If you are using a hot composting method, the pile will be no longer generating a significant amount of heat.
- The compost has a dark crumbly appearance and has an earthy odor.
If your compost is not ready for its intended use, it should be "cured" for a period of time. Curing is the process of allowing compost that has completed the hot phase of composting to finish the composting process. Make sure the compost is moist (see compost moisture content) and aerated during the curing period, which can be as short as one month or as long as a year or more.