Knowledge from Olle Garden Bed: How Long Does It Take For Compost To Mature

Composting is a way for many gardeners to recycle garden waste. Shrubs and plant leftovers, grass cuttings, kitchen waste, etc. can be returned to the soil in the form of compost. Although experienced composters know from experience when their compost can be used, novice composters may need some guidance. The following content also has some reference value for raised garden beds.

Is my compost finished?

There are many variables that affect the completion of composting. This depends on the particle size of the material in the pile, how it is usually used to supply oxygen, humidity level and temperature pile and carbon nitrogen ratio.

How long does it take for compost to mature?

Considering the above variables and the intended use, it may take one month to one year to achieve a mature product. For example, using compost as topdressing takes the least time. When compost is used as the growth medium of plants, finished compost or humus is required. If the unfinished compost is mixed into the soil before reaching the humus stage, it may be harmful to plants.

The finished compost looks black and crisp, with an earthy smell. The stacking is reduced by about half, and organic substances are no longer visible when added to the compost heap. If the hot composting method is used, the pile shall not generate too much heat.

Compost maturity test

There are scientific methods to test compost maturity, but they may take some time. The fastest way is to put some compost into two containers and sprinkle radish seeds. If 75% of the seeds germinate and grow into radishes, your compost can be used. (Radishes are recommended because they germinate and develop rapidly.

More sophisticated methods for calculating germination rates include a "control" group, which can be found at the university's expanded website. The plant toxins in the unfinished compost can prevent the seeds from sprouting or killing the bean sprouts soon after. Therefore, if it is acceptable to reach the germination rate, the compost is considered safe for any application.