Vermicomposting

Also known as worm composting, this is a simple way of turning organic household waste into a useful soil conditioner and fertilizer for houseplants, gardens and lawns. Worm composting can be done year-round and is particularly useful for those who want to compost their food scraps but don't have space for a backyard compost bin.

The process requires a container, half to one kg of redworms, bedding (shredded newspaper, straw) and fruit and vegetable waste.

Fill the container one-half to three-quarters full with damp bedding. Add the worms. Pull aside some of the bedding, bury the food waste and cover it up with the bedding.

Over a period of four to six months, the worms and microorganisms eat the organic material and bedding, producing rich compost.

The container should be 20 to 30 cm deep and provide about 0.2 sq m of surface area for every kilogram of food waste generated per week. A household with two to four people will produce about three kg of food waste a week. This requires a 0.6 m by 1.0 m bin. The quantity of food scraps generated may vary, so scraps should weighed for a couple of weeks to ensure the bin's size is adequate.

Redworms are best for composting because they thrive on organic material such as food scraps. Also called red wigglers, brandlings or manure worms, they can be bought in bulk from a local bait store.

Suitable bedding materials include shredded newspaper and cardboard, chopped up straw and other dead plants, dried grass clippings, peat moss, compost and aged manure. Vary the bedding in the bin to provide more nutrients for the worms and to create rich compost. A couple of handfuls of sand and potting soil (not top soil) will also provide necessary grit for the worms' digestion.

Worms will eat food scraps such as fruit peels and cores, vegetable trimmings, bread scraps, tea bags and coffee grounds. Worms will digest the material more quickly if the scraps are cut in two centimetre pieces. To avoid potential odour problems, do not compost meats, dairy products or oily foods. Discourage fruit flies by always burying the food waste and not overloading the bin. Keep a plastic sheet, piece of old carpet or sacking on the surface of the bedding.

Decomposed bedding and compost should be removed every four to six months. Simply move all the material over to one side of the bin, place new bedding in the space created and add food waste to the new side for the next six to eight weeks. The worms will gradually move over and the finished compost can be removed.