Bedding plays an important role in the worm composting process. It is the environment in which your worms live and eat. Keeping your worms happy and healthy means choosing a suitable bedding and maintaining it properly. The five essential reasons for preparing a worm bedding are:

• to hold moisture in the bin;
• to allow for air circulation;
• to give the worms a moist place to live and work;
• to permit air exchange through the bedding; and
• to control odours.

There are several materials that are suitable for bedding. Remember that worms will eventually eat their bedding, so it must be made from natural materials - fibrous (cellulose) and non-toxic. A table of suggested beddings is attached.

How much bedding is required?
That depends on the size of your bin and the amount of food waste generated in your household. Use the samples below as a guide.

• A 2 ft. x 2 ft. x 8 in. (60 x 60 x 20 cm) box will require 4 to 6 lbs. (1.8 to 2.7 kgs.) of dry bedding.
• A 3 ft. x 2 ft. x 1ft. (90 x 60 x 30 cm) box will require 9 to 14 lbs. (4 to 6.3 kgs.) of dry bedding.

You can use a utility or bathroom scale to weigh your bedding. First, weigh yourself. Then weigh yourself while holding a plastic bag filled with dry bedding. The difference between the two weights is the weight of the dry bedding. Repeat this procedure for the weight of the water described below.

How much water is required?
A worm's body is approximately 75 per cent to 90 per cent water. The bedding should have the same moisture content to allow the worm to breathe easily through its skin. To create a 75 per cent moisture content, create a 3:1 ratio of water to bedding, by weight. Use a scale or pint bottles to measure the weight of water. (One pint = one pound.)

Special Additives
A dd a handful of soil or a tablespoon or two of crushed, dried egg shells or powdered limestone (calcium carbonate) at the initial stage of bedding preparation. This gritty material will help the worms to break down food particles in their gizzards. There are additional benefits. For instance, the crushed egg shells and powdered limestone will add calcium to the bedding, and prevent the material in the bin from becoming too acidic.

Caution: Using your egg shells makes good waste reduction sense. But if you wish to buy powdered limestone, make sure you buy lime that is mixed with feed or agricultural lime. Other types of lime can kill your worms.

Preparing the Bedding
Mix one-half of the bedding with about one-half of the required amount of water in a large mixing container. Add one or two handfuls of soil, crushed egg shells or powdered limestone, then add some more water. Mix until the water is well distributed throughout the container. Add entire contents to worm bin and distribute evenly.

Prior to adding your worms, check the temperature of the bedding to ensure that it is not too hot or too cold. Temperatures above 27 degrees C (81 degrees F) could be harmful to the worms. If the temperature is below 8 degrees C (46 degrees F), the worms may freeze. The most ideal working conditions will occur in temperatures between 13 degrees -25 degrees C (55 degrees - 77 degrees F). Keep in mind that if the temperature is uncomfortable for you to live in, then it will also be uncomfortable for the worms. If the temperature is acceptable, you can add your worms.

* Adapted from literature produced by Mary Appelhof, Flower Press, and Lorraine Johnson.

Different Types of Bedding Materials

• Shredded Newspaper*
  Tear into 1" to 2" strips. Soak overnight in water. Arrange paper in bin. Fluff up any compacted strips.
  Advantages - Provides good bedding.
  Disadvantages - May be messy and will not hold moisture well; water may evaporate due to large surface area. Can heat up and, possibly, self-combust.
  *Avoid coloured newspaper (some inks may contain heavy metals).

• Peat Moss
  Soak overnight in water to reduce the amount of acidity. (To reduce acidity, add six to 12 crushed egg shells). Squeeze out water before using. Mixing one-third to one-half peat moss with another material (see other materials listed) will create a good bedding and will be cheaper than using only peat moss.
  Advantages - Mixes well with other materials. Holds water well. Clean and odourless.
  Disadvantages - Provides no nutrients to the worms. Can be expensive.

• Shredded Corrugated Cardboard
  Tear into shreds and soak in water before using. Mixing with another material will prevent compaction. Do not use waxed, bleached, coloured or white cardboard.
  Advantages - Light and fluffy. Easy to dampen to the proper moisture content. Clean and odourless. Creates good worm castings. Easy to prepare.
  Disadvantages - May be hard to find. Dries on top and edges. Dust may be harmful to breathe.

• Leaves
  Check leaves for insects that you do not want indoors. Do not use leaves that may have been sprayed or contaminated with toxins. Shred leaves, then mix with another material. Layer mixture in bin. Remember to moisten dry leaves.
  Advantages - No cost. Natural worm habitat.
  Disadvantages - Unwanted organisms may be present. Leaves can mat together, making it difficult to bury waste.

• Straw
  Mix one-half straw with one-half peat moss.
  Advantages - Provides a good bedding structure. Light and fluffy.
  Disadvantages - Takes a long time to break down. May be hard to find in urban areas. Extremely high in carbon.