How Does Vermicomposting Work?

Vermicomposting is the process of turning food waste into rich fertilizer using natural decomposition and worms, like redworms. This is done inside a container, often called a worm farm, maintained at a reasonable temperature. A vermicomposting bin is a self-contained ecosystem ventilated by small holes and drained through the bottom. A well-established and balanced worm farm will produce a constant supply of fresh compost as food waste is processed through it.

The Worms

The worms are what make the whole system work. They eat all the food waste that is presented to them and excrete worm castings, which are the refined compost.

Many varieties of earthworms are suitable for employment in a worm farm, but they should be varieties that occur naturally in your area. Worms can escape and are sometimes distributed with the compost. You don’t want to be responsible for introducing a foreign worm to your soil—especially if it is aggressive towards native species.

The Food Waste

Any fruit or vegetable food waste is suitable for composting. Introduce it to the worm farm by simply distributing in the top layer under the cover. Worms naturally forage on the surface, so you don't need to bury the waste food deeply. Ground egg shells and calcium can be added to the food, but no animal products like bones or fecal matter—these materials can rot and attract pests, and they are not good for your plants, anyway.

The Bedding

Provide a medium through which the worms can move a layer of bedding. The bedding can be made of torn newspaper, card board, manure, peat moss and other products. The bedding is eaten by the worms, but is mainly for roughage, so it is consumed more slowly than the nutritious food waste.


Worms breathe through their skin and need it to be moist. Introduce the bedding in a damp condition, as that may enough to keep the whole bin moist. Occasionally sprinkle some water to build up moisture levels. When moisture levels become too low, the first sign is often worms escaping to look for better conditions elsewhere.


Worms can not tolerate high or low temperatures. Try to maintain a temperature of between 55 and 75 degrees. In a way, the temperature is almost self-regulating because the bin is closed. To help keep things working smoothly, keep the bin out of direct sunlight and protected from frost.

The System

The system works very simply. Once you establish the bin, introduce the worms and some food. The worms eat the food and excrete the waste in the form of worm casts that can be used as fertilizer.

Collect the worm compost directly from the bin or by using a series of 2 bins on top of each other. The latter method will allow you to feed the top bin when the bottom bin collects almost all compost. As the bottom bin's last contents are turned into compost, the worms will migrate to the upper bin to find more food. The lower bin can then be emptied and placed on top till it is ready to take over again.