Bedding is a high C/N material that holds moisture, provides an
aerobic medium worms can exist in, and allows you to bury the
garbage in the box. The best beddings are also light and airy,
helping to maintain aerobic conditions. Bedding must not be toxic to
worms because they'll eventually eat it. Bedding starts out dry and
must be first soaked in water and then squeezed out until it is
merely very damp. Several ordinary materials make fine bedding. You
may use a single material bedding or may come to prefer mixtures.
If you have a power shredder, you can grind corrugated cardboard
boxes. Handling ground up cardboard indoors may be a little dusty
until you moisten it. Shredded cardboard is sold in bulk as
insulation but this material has been treated with a fire retardant
that is toxic. Gasoline-powered shredders can also grind up cereal
straw or spoiled grass hay (if it is dry and brittle). Alfalfa hay
will decompose too rapidly.
Similarly, shredded newsprint makes fine bedding. The ink is not
toxic, being made from carbon black and oil. By tearing with the
grain, entire newspaper sections can rapidly be ripped into
inch-wide shreds by hand. Other shredded paper may be available from
banks, offices, or universities that may dispose of documents.
Ground-up leaves make terrific bedding. Here a power shredder is not
necessary. An ordinary lawnmower is capable of chopping and bagging
large volumes of dry leaves in short order. These may be prepared
once a year and stored dry in plastic garbage bags until needed. A
few 30-gallon bags will handle your vermicomposting for an entire
year. However, dry leaves may be a little slower than other
materials to rehydrate.
Peat moss is widely used as bedding by commercial worm growers. It
is very acid and contains other substances harmful to worms that are
first removed by soaking the moss for a few hours and then
hand-squeezing the soggy moss until it is damp. Then a little lime
is added to adjust the pH.