The bin will need to be about 1/3 to 1/2 full of bedding. A 10 gallon bin is suitable. To create bedding, soak a large quantity of shredded newspapers or cardboard. Worms like an environment that is 75% water. Newspaper will be thoroughly soaked in only a few minutes. If you are soaking cardboard such as the inner rolls of toilet paper or paper towels, you may have to soak it overnight. All papers can be eaten, but the coarser the texture the more the worms will like it. Don't use paper or cardboard that has colored ink on it. Colored inks sometimes have metals in them that are toxic to worms. If you have access to shredded paper from work, that is perfect for bedding. Leaves can also be used.
After the bedding is soaked thoroughly, wring it out until it is no longer dripping. Fluff it up by separating the strips. Place it into the bin. One-third to 1/2 of the bin should be full of bedding.
Worms don't have teeth, so they need something gritty to use in grinding up the paper and food. Put a little bit of soil, fine sand, leaves, and sawdust or ground egg shells to provide grit. Once your operation is underway, the castings will provide grit so you don't need to add more unless you clean out your bin and start over.
Put the worms into the middle of the bedding. Don't just set them on top. Place the lid on the bin. The worms will die if they are not kept at moderate temperatures, so keep an inside container indoors or somewhere the temperature does not get hot (90 degrees F or more) or cold (40 degrees F or lower). Some people keep them under the kitchen sink for convenience. Worms in outside bins dig down into the ground when temperatures become extreme.
Make sure worms are away from high traffic areas. They don't like to be disturbed by loud noise or abrupt movements or vibrations.
Leave the worms for a week or so and let them start eating on the paper bedding before you add food.
Acceptable foods are: fruit rinds, cores and peels, grains, vegetative matter, egg shells, coffee grounds and filters, tea leaves and bags. They like materials high in cellulose such as sawdust, leaves, paper and cardboard. Unacceptable foods are: oils, cat and dog manure, meat, cheese, butter, animal products, fish, and paper with colored inks. Materials will be eaten faster if you chop food wastes first.
Worms should be fed about once a week. It is much better to give them small amounts of food on a weekly basis.
At feeding time, check that the bin is not accumulating liquids from the foods. If it is, use paper bedding to soak up the liquid. Next, check for excessive accumulation of undigested foods. If you have a lot of food which the worms did not digest, you must monitor the situation.
Make sure the bedding is still wet. If it is not, use a spray bottle filled with water to thoroughly wet the bedding. Don't make it so wet it drips water.
Put a few tablespoons of kitchen scraps under the top layer of bedding. You may need more than a few tablespoons depending on the size of your bin, the number of worms you have, etc. Worms are expected to eat a pound of food per week for every square foot of surface space in their bin. The real test of the correct amount of food is attention to what remains at the end of the week. Replace the bedding to cover the scraps. Replace the lid on the bin.
Castings should be harvested about twice a year. When most of the bedding has been eaten, it is time to harvest the castings and add new bedding.
"Harvesting" the castings means removing finished castings from the bins while leaving the worms in the bins to make more castings. To do this, the worms must be separated from the castings they currently inhabit without excessive handling.
There are two common ways to harvest the castings. The first method is recommended. Move everything (worms, castings, partially decomposed paper and food) to one side of the bin. Pick out the partially decomposed materials and put them on the empty side. Place food on top. Cover the food with fresh paper strips. Replace the lid and leave the bin. Within a few weeks, the worms will have finished whatever edible remained in the finished castings, and will move over to the new bedding and food. At that point, remove the castings from the bin (wear gloves). Carefully review or sift to make sure you leave all worms in the bin.
The second method utilizes the fact that worms hate light. This method is less desirable because worms hate being handled and because it requires more effort. Take finished castings and worms out of the bin. Make a pile of the earth castings (worms will be mixed in there) and shine a light on it. The worms will move to the middle of the pile in order to get away from the light. Brush off the outside layer of worm-free castings with a very soft brush. The worms will move closer to the middle to avoid the light. Brush off the outside worm-free layer again. Repeat this until you are left with a ball of worms. Return the worms to the bins. Wash your hands thoroughly after handling castings and/or worms.
Add new bedding to the bin until it is 1/3 to 1/2 full.