The Disadvantages of Vermicompost

worms image by Adrian Hillman from

Vermicomposting systems contain earthworms that speed of decomposition of organic materials. These worms feast on items such as produce, kitchen scraps and coffee grounds, transforming the waste into an eco-friendly fertilizer called humus. While vermicomposting offers substantial environmental benefits, it also is associated with a number of potential problems that users should be aware of before setting up a new compost system.

Environmental Requirements

Earthworms in vermicompost systems can stay alive only when temperatures range from 50 to 80 degrees Fahrenheit, according to the Iowa Department of Natural Resources. This may prohibit vermicomposting efforts in very cold or hot climate zones. If the average temperature in your area falls outside of this range, consider a small indoor vermicompost system. Many homeowners prefer to keep compost units outdoors, making vermicompost impracticable in many areas. Even if you're able to maintain the required temperature, it’s mandatory to keep an eye on moisture and ventilation to avoid additional problems. Inadequate ventilation or excess moisture leads to sour odors in the bin, and can kill the worms. Finding the right level of air and moisture within your system often requires experimentation.

Limited Media

Earthworms require a controlled diet to survive and produce humus. These worms have gizzards instead of teeth, making them unable to break down some materials. Homeowners should avoid placing any inorganic materials in the bin, including foil or food packaging, according to the Yale-New Haven Teachers Institute. Worms also have difficulty digesting meat, dairy or greasy foods, so these items must be placed in a standard compost bin or a regular garbage receptacle. Worm-friendly foods such as fruit, vegetables, bread or coffee should be added twice a week and mixed with the bedding to keep the worms alive and maintain the system.

High Cost

While it's possible to make a vermicopost unit out of wood or scrap materials, pre-manufactured units offer the best performance, according to the Yale-New Haven Teachers Institute. Engineered units feature easy-to-use trays and openings that allow for the addition of waste or removal of worm casings and humus. Homemade units often have poor ventilation and moisture control, which makes it difficult for worms to thrive and may cause odors or encourage fruit flies. Pre-manufactured vermicompost units cost as much as $25,000, depending on size and features, according to the Iowa Department of Natural Resources. With 2 lbs. of worms required per 1 lb. of waste added, many users require systems of substantial size that come with hefty price tags.