Vermiculture, the practice of raising earthworms, transforms organic household waste and kitchen scraps into a usable soil amendment through the digestive processes of worms. This activity requires minimal space and can be adapted for indoor or outdoor settings.
Creating the Worm Habitat
The foundation of a successful worm farm is the container, or bin, which can be constructed from a plastic tote or purchased as a commercial unit. Proper aeration and drainage are necessary, so holes should be drilled into the bottom and sides of the bin to allow excess moisture to escape and air to circulate. For a do-it-yourself system using stacked boxes, the top box where the worms reside should have holes in the bottom, while the lower box catches liquid drainage, often called leachate.
Inside the bin, a prepared bedding material provides the living medium for the worms. This bedding is not soil but a mixture of materials that hold moisture and provide a carbon source, such as shredded newspaper, cardboard, aged compost, or coconut coir. Before adding worms, this material must be moistened to the consistency of a damp sponge. The bin should be filled about three-quarters full with this fluffy, damp bedding.
The type of worm used is specific to composting environments, as common garden earthworms are not suitable for the confines of a bin. The most effective species is the Red Wiggler, or Eisenia fetida, which thrives in the dense, organic material of a worm bin rather than in soil. These worms can be sourced from commercial growers, and introducing about one pound of worms is a good starting point for a new bin.
What to Feed Earthworms
A consistent and appropriate food supply is necessary for a productive worm farm. Worms consume a variety of kitchen scraps, including fruit and vegetable peels, cores, and rinds. Coffee grounds, tea bags, and crushed eggshells are also excellent additions; eggshells provide grit that aids the worms’ digestive process. It is helpful to cut or break down larger food items into smaller pieces, which accelerates their decomposition.
Certain foods must be avoided to prevent odors, pests, and an unhealthy bin environment. Do not add the following:
- Meat, fish, bones, and dairy products, as they can rot and attract unwanted animals
- Oily or greasy foods
- Large quantities of citrus peels, which can increase the acidity of the bedding to harmful levels
- Onions and garlic, due to compounds that can be detrimental to the worms
When feeding, bury the food scraps under the bedding material. This helps to deter fruit flies and other pests and keeps the food moist, making it more accessible to the worms. A common mistake is overfeeding, so add new food only when the previous batch has been mostly consumed, which might be a few handfuls every few days for an established colony.
Maintaining Bin Conditions
Moisture level is a primary factor; the bedding should consistently feel like a wrung-out sponge. If the bedding becomes too dry, it can be sprayed with water. Conversely, if it becomes too wet, adding dry, shredded newspaper or cardboard will help absorb the excess moisture and prevent the worms from drowning.
Temperature is another important consideration. Red Wigglers perform best in temperatures between 60 and 80 degrees Fahrenheit (15-27 degrees Celsius). Bins kept outdoors should be placed in a shaded, sheltered location during hot summer months and moved indoors during cold winters to protect the worms from extreme temperatures. Proper aeration, achieved by fluffing the bedding weekly, supplies the worms with oxygen.
Harvesting and Using Vermicompost
After several months, the bedding and food scraps will be converted into dark, nutrient-rich worm castings, also known as vermicompost. To harvest this material, separate it from the worms. One effective technique is the light migration method, where the contents of the bin are spread onto a tarp under a bright light, which causes the light-sensitive worms to move downwards into the pile.
Once the worms have migrated down, the top layer of finished vermicompost can be scraped away. This process can be repeated every 15-20 minutes, allowing the worms time to burrow deeper into the pile. The harvested castings have a fine, soil-like texture and can be mixed into the soil of houseplants or garden beds. The remaining worms and any unprocessed material can be returned to the bin with fresh bedding to restart the cycle.