Getting Started in Vermicomposting

When beginning a vermicomposting bin, put moist bedding into the bin, and add as many composting worms as available. In hot climates place the bin in the shade or away from midday direct sun. Quantities of kitchen waste appropriate for the worm population can be added to the bin daily or weekly. At first, feed the worms approximately one-half their body weight in kitchen scraps a day, maximum. That is, if you have 1 lb. of worms, feed them about 1/2 lb. of kitchen scraps a day. After they have established themselves, you can feed them up to their entire body weight. It is best not to add new food until the old food has been processed by the worms. 




Bedding is the living medium for the worms but also a food source. It is material high in carbon and made to mimic dried leaves on the forest floor, the worms' natural habitat. The bedding should be moist (often similar to the consistency of a wrung-out sponge) and loose to enable the earthworms to breathe and to facilitate aerobic decomposition.  A wide variety of bedding materials can be used including newspaper, sawdust, hay, cardboard, burlap coffee sacks, peat moss, pre-composted (aged) manure, and dried leaves.  Most vermicomposters avoid using glossy paper from newspapers and magazines, junk mail and shredded paper from offices, because they may contain toxins which would severely affect the system. Also some cardboard cannot be used if it contains wax or plastic, such as cereal boxes, and other boxes designed to hold food items. Newspapers and phone books printed on regular, non-glossy pages are heavily regulated by the Food and Drug Administration (FDA) and use non-toxic soy and Canola based ink. Some beddings are easier to use and add food scraps to than others. 




Worms used in composting systems prefer temperatures of 55 to 70 degrees Fahrenheit (12-21 degrees Celsius). The temperature of the bedding should not drop below freezing or above 85 °F (29 °C). 


Kitchen waste 


Greens—If too much kitchen waste is added for the worms to process, the waste putrifies.  A balance between “green matter” such as kitchen scraps and “brown matter” such as shredded newspaper for bedding must be maintained in order for the worms to do their work. This is often called "carbon to nitrogen ratio", and should be approximately 2:1 (C:N). Covering the kitchen scraps with a layer of "brown matter" has the added benefit of reducing odor and insect problems. Avoid grass clippings or other plant products that have been sprayed with pesticides. In a small bin, this includes banana peels which can kill everything in the bin, if heavily sprayed. 


Meats—Although proteins and fats in meat scraps can be processed by a vermicompost bin, doing so tends to attract scavengers and should be avoided if this is a risk. Worms are unable to break down bone or synthetic material. 


 Over the long term, care should be taken to maintain optimum moisture levels. In a non-continuous-flow vermicomposting bin, excess liquid can be drained via a tap and used as plant food. A continuous flow bin does not retain excess liquid and requires extra water to be added to keep the bedding moist. 


The pH level should be near neutral or slightly alkaline. Coffee grounds have sometimes been blamed for acidity, but analysis shows they are only mildly acidic with a pH of 6.2. Too much oil or fat can hinder the breathing of the worms, as they breathe through their skin. Worms are said to not like highly spiced foods such as onions, garlic, or heavily salted foods.  Worms and other microorganisms in the composting process require oxygen, so the bin must "breathe". This can be accomplished by regularly removing the composted material, adding holes to a composting bin, or using a continuous-flow bin. If insufficient oxygen is available, the decay becomes anaerobic, like that in swamps and bogs, producing a strong odor offensive to most people. 




There are two methods of adding matter to the bin.


  Top feeding — organic matter is placed directly on top of the existing layer of bedding in a bin and then covered with another layer of bedding. This is repeated every time the bin is fed. 


Pocket feeding — a top layer of bedding is maintained and food is buried beneath. The location of the food is changed each time and often the bin is fed in more than one location. As bedding runs low more is added. 


Vermicomposters often use a combination of both methods. Sometimes unburied food can attract fruit flies. For this reason, food should be buried at least one inch under the surface of the bedding material. 




Odor , usually due to overabundance of "greens" in the bin, actually too much nitrogen combining with hydrogen to form ammonia. To neutralize the odors, add a fair amount of carbon to the mix. The carbon will absorb the nitrogen and form a compound that is not smelly. Paper and dried leaves are good sources of carbon. But too much carbon slows the decomposition process considerably. 


Pests such as rodents and flies may be attracted by certain materials and odors, especially lots of kitchen waste and especially meat. This problem is largely negated if a sealed bin is used where the pests cannot access the material. Local authorities usually advise to avoid pests by avoiding using materials that attract them, rather than relying on special containers. Ants can become a problem as well. No-see-um netting can be used. Regular mosquito window screen is too large and lets fruit flies and possibly ants in as well.  Red Wiggler worms are not native to North America. They are an invasive species and have become naturalized in most of the globe. Do not dump worm-containing compost in natural areas as they can have the effect of displacing the native worms.