Vermicomposting is the practice of using specific species of earthworms to convert organic waste materials into a rich soil amendment called vermicompost, or worm castings. This process offers significant environmental benefits by diverting food scraps and other organic matter from landfills, where they would otherwise produce methane gas. Specialized worms are required for this method because they thrive in the high-concentration organic environment of a composting bin. The resulting worm castings are a nutrient-dense product that enhances soil health and plant growth.
The Ideal Worm Species for Vermicomposting
The success of a vermicomposting system depends on selecting the right worm species, which are known as epigeic, or surface-dwelling, worms. The two most commonly used species globally are the Red Wiggler (Eisenia fetida) and the European Nightcrawler (Eisenia hortensis). These worms are naturally adapted to living and feeding within decaying organic matter, such as leaf litter and manure.
Red Wigglers are highly prized for their rapid reproduction rate and tolerance for a wide range of conditions, making them the preferred choice for beginners. They are voracious eaters, capable of consuming half their body weight in food scraps each day under ideal circumstances.
European Nightcrawlers are larger than Red Wigglers and tend to process organic material slightly slower, but they are also excellent composters. They are somewhat more tolerant of temperature fluctuations and are often favored when the finished vermicompost is used for fishing bait, due to their size. Both species are highly communal, meaning they thrive in the dense, contained environment of a composting bin without attempting to escape. They are detritivores, consuming the decaying organic matter and the microorganisms that are breaking it down, converting it efficiently into castings.
Distinguishing Composting Worms from Garden Worms
Earthworms are categorized into three ecological groups: epigeic, endogeic, and anecic. Composting worms are epigeic, living on the surface and feeding primarily on fresh organic material. Common garden worms are typically endogeic or anecic species, such as the Canadian Nightcrawler (Lumbricus terrestris).
Anecic worms create deep, permanent vertical burrows and pull surface organic matter down to eat, while endogeic worms burrow horizontally and consume soil. These deep-burrowing species require mineral soil and will not survive in the highly concentrated, moist organic environment of a typical worm bin. Attempting to use them will result in the worms dying or attempting to leave the bin in large numbers, as the conditions do not suit their natural habitat.
Sourcing and Establishing Your Worm Colony
Once the correct species is chosen, acquire them from a reliable source, such as a dedicated online worm farm, a local composting facility, or a specialized bait shop. It is important to confirm the species being purchased, as a healthy colony is the foundation of a successful bin. The worms must be introduced into a bin that has been properly prepared with suitable bedding material.
Bedding provides a habitat and a source of carbon, and common materials include shredded newspaper, peat moss, or coconut coir. This bedding must be thoroughly moistened to a consistency similar to a wrung-out sponge, which is a moisture content of about 65 to 85 percent. Worms breathe through their skin and require this high moisture level to survive, but the bin must also have adequate drainage and ventilation to prevent anaerobic conditions.
The optimal temperature range for Red Wigglers is between 59 and 77°F (15 to 25°C), which encourages the fastest feeding and reproduction. Keeping the bin within this range ensures the worms remain productive. When first introducing the worms, feed them very small amounts of food scraps until the colony has acclimated and established itself in the new environment.