Indoor Worm Bin Composting

You can use red worms to recycle your food waste by setting up a worm bin recycling system in your school classroom or at home in your kitchen, basement, garage or yard. A worm processes half its own weight in food scraps every day! Red worms transform soil and decaying plant material into an excellent plant fertilizer and soil amendment called vermicompost. Your food waste will disappear while your worms produce a valuable product

To start recycling your food waste with worms, you need to buy or construct a worm bin and obtain a few pounds of red worms.

Red Worms

When you order red worms from a supplier, you will get Eisenia foetida or Lumbricus rubellus. Either of these species will effectively recycle your food waste and will thrive in a worm bin.

Red worms eat fruit and vegetable scraps, crushed egg shells, coffee grounds, tea bags and leftover bread and grains. They do best not trying to eat meat or fish scraps or fatty, oily foods.

The number of worms you need depends on how many pounds of worm food your family generates each week. If you stock your worm bin with two pounds of worms (about 2000), it should be able to process a pound of food scraps a day, or 7 pounds a week. The amount of worms you need dictates what size worm bin you use.

Worm Bin

Worm bins can be purchased, or you can make your own by building or adapting a wooden or plastic box. About one square foot of surface area is needed for each pound of worms. The box should be shallow (8-12" deep) because red worms feed only in the top few inches of bedding material. A lid is necessary to keep conditions moist and dark. About ten half-inch holes should be drilled in the top for air circulation and drainage, and there should be air holes along the top of the side walls as well.

Add about four inches of moistened bedding materials, such as leaves, potting soil or one-inch strips of newspaper. Water should be sprinkled onto the bed to achieve a moisture level equivalent to that of a wrung-out sponge. Add food to the bottom of the bin, under most of the bedding, leaving no food exposed on top. To add your worms to the bin, lay them on top of the bedding and leave the lid off for a while; since worms are sensitive to light, they will burrow into the bedding.

You can keep your worm bin in your classroom, kitchen, basement or garage all year round, or it may stay outdoors at temperatures between 50 and 80 degrees F.

Feeding Your Worms

You can feed your worms small amounts every few days or their whole week's food supply at one time. Large items, such as broccoli stalks, should be cut up. Move some bedding aside, add your food waste and then cover it back up. Each time you feed the worms, bury the food scraps in a different part of the bin. Worms will eat both the food and the bedding, producing dark, rich compost.

Harvesting Your Vermicompost

When the bedding starts to resemble dark, crumbly soil (usually in one to four months), it is time to harvest your vermicompost. Move all the bedding over to one side of the worm bin. Add new dampened bedding to the empty side, and start placing food waste on that side. Over a one month period, many worms should move over to the new bedding, allowing you to scoop out the vermicompost. Manually separating worms from the finished compost may also be necessary if you wish to hold on to all worms for the bin. Vermicompost starts becoming toxic to the worms if left in the worm bin for too long.

How to Use Your Vermicompost

Vermicompost is an excellent source of both slow-release and immediately available nutrients. Because it contains humus and decomposing plant material, it will help to add moisture and nutrients to the soil.

Sprinkle vermicompost into your seed rows to give your plants a source of nutrients when they sprout. When you transplant, throw a handful into the hole before you plant. You can also use vermicompost as a top-dressing for your plants.


An odor problem signifies that the recycling system is malfunctioning. Make sure you cover your food waste with bedding. If the problem persists, there is probably not enough oxygen in the bin, indicating an overload of food. Start a temporary bin with a portion of your worm bin contents and the problem should resolve itself.

Fruit flies sometimes become a pest in and around worm bins. Taking steps to avoid an infestation is easier than getting rid of one. Wash fruit, including banana and citrus peels, before placing it in the bin. Make sure to bury the food and avoid putting in any rotten food, since it is likely to have fly larvae on the skin. Avoid overfeeding the bin and do not keep it overly wet. Placing an extra section of dry, folded newspaper sheets on top of the bedding also makes the surface of the bin less inviting for flies to lay eggs. If fruit flies become a problem, you can try fly paper traps or stop adding fruit until the problem subsides.

Patricia Jasaitis

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