Vermiculture or

Worm Composting


Many municipalities prefer that food wastes NOT be composted in the backyard compost pile. This restriction helps with issues of pests and odors. A popular way to compost food wastes and small amounts of paper is a worm compost bin.

Red worms (commonly called red wigglers) and brown-nose worms can be used to compost food scraps and paper. Worm compost bins have been called organic garbage disposals. The worms live in paper bedding into which kitchen scraps are placed. They eat both the paper and the kitchen scraps and excrete worm castings. Castings are far more potent than compost made from a backyard pile. There are more nutrients in castings, and they are in a form that makes them even more readily available to vegetation.

People often question why this process doesn't smell. It is actually the rotting portions of decaying food that stink. In worm composting, the worms eat the rotting portion. The fresh portion is then exposed to the air and begins to rot. The worms eat it as it rots. As long as you don't put in too much food for the worms, they will eat the food as it rots. Therefore, there is no rotting food left to create an odor. (If your bin smells, you are providing the wrong kinds of food or too much food.)

Use the following links to access complete instructions on setting up and operating a worm compost bin:


The Worm Bin

You can either build a bin or buy one. Building a bin is not difficult. The following list of factors should be reviewed whether buying or building a bin:

  • Worms like a dark, moist environment. They hate light.
  • Liquids are released from some foods as they rot, especially fruits.
  • Worms need to breath.
  • Worms need to be protected from pests which would be attracted to rotting food left in the open.
To build an inside bin, get a 5- or 10-gallon plastic tub with a lid that snaps shut. Do not get one made out of translucent plastic. Opaqueness is required to produce the dark environment worms like, and plastic holds in moisture. A tight lid will keep pets and pests out.

A word about the size of the bin: I have heard recommended sizes of 12"L x 10"W x 10"H and 1' x 2' x 3' box. Mine measures 19"L x 15"W x 10"H. When choosing or making a bin, surface area (L x W) is more important than depth ,i.e., heighth of the bin (H). One square foot of surface area is required for every pound of food waste to be composted per week.

Punch 1/8" holes about 1 " apart all the way around the sides of the bin to provide air for the worms.

Punching holes in the bottom of the bin is an option, but not one I recommend. If you punch holes in the bottom, you will also need a plastic tray to place under the bin at all times. If liquids accumulate in the bottom of the bin, they will drain out into the tray. This liquid will attract pests such as ants and flies, so you must keep the tray and the bottom of the bin clean at all times. The reason I don't like this option is because it seems like a lot of trouble to me. If excess moisture accumulates at the bottom of the bin, just use dry strips of newspaper to absorb it and leave them in the bin as bedding.

Bin Another option is an outside bin. An outside bin can handle a larger amount of food. Using wood and/or cinder blocks, build a box meeting the same requirements as those above except that the bin can be much larger -- 4'W x 3'L x 2'H. It still requires a tight lid if you are going to compost food scraps which can be attached with sliding and locking galvanized hinges. If you are only composting leaves and hay, no lid is needed. Remember to keep moist. Bedding and feeding instructions below are the same for an outside bin.

Bin We had a large outdoor bin built from wood at our Home Demonstration Site. It did not withstand the natural elements very well. It was replaced by a bin that was made of stacked cinder blocks with a hinged wooden lid. So far, this one is working very well. For instructions on constructing a large outside bin, see

  • Worm Composting Bin Instructions from the University of Missouri Extension Service


    Top of Page

    The Worms

    Red worms (commonly called red wigglers) and brown-nose worms can be purchased at some garden supply stores, bait shops, and worm farms. You need about a pound of worms for each pound of kitchen waste per week you would like to compost. (These are not common earthworms, which will die in the worm composting environment because there is not enough soil.)

    Worms can double their populations every 90 days. As long as you give them adequate food and a good environment, the worms you buy will expand their population to fill your bin, so you shouldn't have to buy more unless you want to increase your worm composting operation very quickly.

    Top of Page

    Setting Up House

    The bin will need to be about 1/3 to 1/2 full of bedding. 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, 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. I keep mine in the garage. 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.

    Top of Page

    Feeding Worms

    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. I have read that they like breads, but mine won't touch bread. Unacceptable foods are: Oils, cat and dog feces, meat, cheese, butter, animal products, fish, paper with colored inks. Materials will be eaten faster if you chop food wastes first.

    I keep a large margarine tub in my refrigerator to accumulate scraps for my worms. This refrigerated container keeps them from drying out, smelling up my kitchen, or rotting too fast before I use them for worm food.

    Worms should be fed about once a week. It is much better to give them small amounts of food on a weekly basis. I, however, have heard of people who feed every 3 weeks or so and have no problems.

    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 accumulateion of undigested foods. If you have a lot of food which the worms did not digest, you must monitor the situation. (See FAQ ).

    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.

    Top of Page

    Harvesting Castings

    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.

    For application instructions for finished castings, see the "Application of Worm Castings" section of Use and Application of Compost.

  • Advertisements
    Online Stores
    Compost Tea Brewer
    Build a brewer with a bucket and less than $15 worth of components, and make aerated compost tea.
    Composting the Holidays
    Compost fall leaves, hay bales, holly wreaths, pine trees, etc. Compost pumpkins (food waste) in a compost pile.



    1. ** Worm Composting **
    2. Use Finished Castings

    Return to Compost Site Contents

    Make Your Own Brewer
    Brew Compost Tea at Home!

    eBook $9.95
    Download Now!

    Make Your Own Brewer
    Brew Compost Tea at Home!

    eBook $9.95
    Download Now!

    Return to Home Page  /   eBooks  /   Return to Compost Site Contents
    Home Page URL:
    Use of this web site constitutes acceptance of all terms in our Terms of Use.
    Copyright - © 2005, Mary J. Tynes.