Indoor Composting

Indoor (Worm) Composters

Indoor composting is done with worms, and is also called vermicomposting. It is an easy and efficient way to compost organic wastes in an apartment, house, office or school classroom. Vermicomposting takes place in an enclosed container. To build your own, the container should be perforated to allow air in. Drainage holes are required in the bottom and air vents in the sides to maintain the right moisture and air levels. The dimensions of the container will depend on the amount of waste you need to process. Surface area is more important than depth. You will need approximately 30 cm (one square foot) of surface area for every pound of food waste to be composted per week.

The Worms

The worms used for vermicomposting are called red wigglers. These worms are not found outdoors as they live in temperatures between 15 degrees Celcius and 25 degrees Celcius. They are efficient processors of food waste and other organic materials, producing dark and fertile compost. The worms reproduce quickly. If you know someone with an active vermicomposter, they will probably have enough worms to give you a “starter” amount. Otherwise the worms can be ordered with the vermicomposter unit or sold separately.

What do the Worms Eat?

You can compost all of the kitchen wastes listed in the DO COMPOST list in your vermicomposter. The worms will also efficiently process small amount of meat or fish waste. Yard materials, because of their volume, are unsuitable for this composting method.

Getting your Vermicomposter Started

  • The ideal bedding for the worms is shredded newspaper. There should be enough newspaper to fill 2/3 of the container. Soak the bedding in water and place it in the vermicomposter.
  • Add the worms. Leave the lid off the composter for about an hour. The worms are sensitive to light and will burrow into the bedding when the lid is off.
  • You can now add kitchen wastes to the bin. Dig a small hole in the bedding, add the waste, and cover the hole. You may want to mark the spot with a twig, or a popsicle stick or other marker so that you can add the next day’s waste in a different spot.
  • The most important part of vermicomposter maintenance is keeping moisture levels the same as a wet sponge. Add water or wet wastes if the material becomes dry. Add more shredded newspaper if the bedding is too wet.

Harvesting from the Vermicomposter

It will take between 3 and 6 months for the bedding and waste in the composter to turn into finished compost. When the compost is ready, it will be a dark, uniform material with an earthy smell. You can harvest the compost in two ways:

  • The slow way to harvest the compost is to move the contents in the bin to one side and add fresh bedding (and waste) to the other. After about one month, the worms will occupy only the fresh bedding and you can then remove the compost.
  • The quick way to harvest the compost is to open the bin under a bright light. The worms will retract into the compost, so that you can remove the upper layer of material. Continue until only a thin layer with the worms in the bin remains. You can then add fresh bedding and start over.