Home composting guide

How does it work

Composting happens when small organisms such as harmless bacteria, enzymes and fungi are given a chance to 'eat' organic waste. This process breaks down the waste and changes its structure so that plants and trees can extract nourishment from it. Also, the waste produced by them, and by worms in the compost heap, increases the nutritional value.

There are several ways of making compost, but it’s a simple process. It will manage itself, but with a bit of help from you, the process is faster and the end product better.

The ingredients of good composting are simple: organic materials, air and water. The materials used to make compost should be a balanced mix of wet and dry, woody and sappy and should provide the right ratio of nourishment. In practice, that means that all your fruit and vegetable waste and most of your garden waste is suitable. To create the right balance, you should aim for a 50:50 ratio of greens, for example, food waste and browns, for example, cardboard, dried leaves and sticks.

Microbes need air like any other organism, so it’s important to turn the compost heap regularly to let air in. Water is important too, as many bacteria and other organisms in the heap can't do their job if it’s too dry. Moisture also helps regulate the temperature of the heap, ensuring the most efficient breakdown process. You can test the moisture content of your compost by picking up a handful and then squeeze it. If water comes out of the compost, it’s too wet. If the compost falls apart in your hand, it’s too dry.

The composting process takes from a few months to two years depending on how you manage the heap, which materials you add and the conditions. A heap turned every week or so and managed under all the right conditions may compost in a few months. An unturned heap will often take about six months to two years to fully compost.

Three simple steps to great compost

  1. Buy or build a suitable bin
  2. Get a good balance of wet and dry materials
  3. Turn the compost with a spade or fork now and then