Redworms are capable of very rapid reproduction at room temperatures in a worm box.  They lay eggs encased in a lemon-shaped cocoon about the size of a grain of rice from which baby worms will hatch.  The cocoons start out pearly white but as the baby worms develop over a three week period, the eggs change color to yellow, then light brown, and finally are reddish when the babies are ready to hatch.  Normally, two or three young worms emerge from a cocoon.

Hatchlings are whitish and semi-transparent and about one-half inch long.  It would take about 150,000 hatchlings to weigh one pound.  A redworm hatchling will grow at an explosive rate and reach sexual maturity in four to six weeks.  Once it begins breeding a redworm makes two to three cocoons a week for six months to a year; or, one breeding worm can make about 100 babies in six months.  And the babies are breeding about three months after the first eggs are laid.

Though this reproductive rate is not the equal of yeast (capable of doubling every twenty minutes), still a several-hundred-fold increase every six months is amazingly fast.  When vermicomposting, the worm population increase is limited by available food and space and by the worms’ own waste products or casts.  Worm casts are slightly toxic to worms.  When a new box starts out with fresh bedding it contains no casts.  As time goes on, the bedding is gradually broken down by cellulose-eating microorganisms whose decay products are consumed by the worms and the box gradually fills with casts.

As the proportion of casts increases, reproduction slows, and mature worms begin to die.  However, you will almost never see a dead worm in a worm box because their high-protein bodies are rapidly decomposed.  You will quickly recognize worm casts.  Once the bedding has been consumed and the box contains only worms, worm casts, and fresh garbage it is necessary to empty the casts, replace the bedding, and start the cycle over.  How to do this will be explained in a moment.  But first, how many worms will you need to begin vermicomposting?

You could start with a few dozen redworms, patiently begin by feeding them tiny quantities of garbage and in six months to a year have a box full.  However, you’ll almost certainly want to begin with a system that can consume all or most of your kitchen garbage right away.  So for starters you’ll need to obtain two pounds of worms for each pound of garbage you’ll put into the box each day.  Suppose in an average week your kitchen compost bucket takes in seven pounds of waste or about one gallon.  That averages one pound per day.  You’ll need about two pounds of worms.

You’ll also need a box that holds six or seven cubic feet, or about 2 x 3 feet by 12 inches deep.  Each pound of worms needs three or four cubic feet of bedding.  A better way to estimate box size is to figure that one cubic foot of worm bin can digest about one pound of kitchen waste a week without going anaerobic and smelling bad.