From the Rotline: How Long Until My Compost Is Ready To Use?

Rotline Question:

How long will it take until my compost is ready to be used?

Answer:

The timeline for composting depends on a number of factors. There are three basic approaches to composting which can be mixed and matched based on resources available and the composter’s goals. They are passive composting, active composting, and hot composting.

Passive composting (also referred to as cool, continuous composting) requires the lowest levels of engagement for pile set-up and maintenance and accordingly, takes the longest to produce finished compost, usually sometime between 6-18 months. Active composting requires more time and effort for set-up and maintenance but can produce compost in 5-6 months. Hot composting is the most time and labor intensive of all the methods, but yields finished compost in the shortest period of time, usually in 3-4 months.

Consider the following factors when estimating how long your pile will take to fully decompose: 

• Particle Size – Chopping pile contents into small pieces increases the surface area of the material, allowing for more rapid decomposition. 
• Volume of Material- Filling or nearly filling a bin at the start (as is common practice in hot composting) supports a larger community of microorganisms (especially heat-loving bacteria) and creates an environment that fosters more efficient decomposition.  In general, piles with higher internal temperatures produce a finished product more rapidly. 
• Water- Keeping a pile evenly moist supports a more efficient community of decomposers, and is essential to speedy decomposition. Aim for the contents to be the dampness of a wrung-out sponge. 
• Turning- Turning a pile approximately once or twice a month helps to mix materials and create air pockets, which support a more diverse and fruitful decomposer population and increases the speed at which materials break down. 
• Curing- Immature compost can kill seedlings and beneficial organisms, so make sure your compost has been cured before use. Curing is the penultimate stage of composting, referring to a period where pile contents cool, rest, and complete decomposition without the addition of new materials. Curing usually lasts 2-4 weeks.