What Kind of Earthworms Do We Recommend?


At this time, there are over 4,400 species of earthworms that have been identified by taxonomists. While some scientists have divided these into three primary groups (epigeic, i.e. “litter dwelling,” anecic, “burrowing, soil dwelling,” and endogeic “deep soil”), a two-fold division seems more convenient: Earthworkers are worms such as the common nightcrawler (Lumbricus terrestris) an excellent earthworm for gardens because it creates burrows, mixes soils and improves tilth. While these are desirable for your garden, they are difficult if not impossible to grow in bins. Composting earthworms, on the other hand, dwell exclusively in organic matter that they process and transform into an extremely valuable bio-fertilizer and bio pest-control agent, castings. It is not recommended that you put these directly into your garden, because they will not create burrows.

At VermiCo, we’ve chosen to focus on one species, Eisenia fetida, (pronounced eye-SEN-ee-uh FE-ti-duh) a composting earthworm, for several reasons. First, it is a durable earthworm, well-suited for the rigors of harvesting and shipping. Second, it tolerates a wide range of temperatures—from nearly 90 degrees Fahrenheit to nearly freezing. (Other, more exotic species are less tolerant of temperature extremes). Third, Eisenia fetida earthworms (also called redworms or red wigglers) are extremely prolific, largely due to consistent production of cocoons with remarkable hatching rates of young that reach sexual maturity in as few as seven weeks. Some have claimed these earthworms, when conditions are optimal, can double their biomass (weight of live earthworms) in 60-90 days. And finally, redworms are the most commonly used species throughout the vermicomposting industry. For obvious reasons, an earthworm that is the most widely used and traded will have the greatest demand and value.

A conservative guestimate is that E. fetida earthworms process at least ½ their body weight per day in organic material. However, this amount depends on the presence of key process variables—temperature, moisture, porosity, and quality of feedstocks. These earthworms are capable of consuming their full body weight and even 1-1/2 times their weight when conditions are right. Their food consists primarily of microorganisms within decomposing organic matter where carbon sources (such as dried leaves, shredded paper, cardboard) have been mixed with nitrogen sources (such as vegetative food waste, grass clippings, manure). Earthworms thrive best in a warm, very moist, aerobic, dark, little-disturbed environment of 100% decomposing organic matter. Toxic elements such as salt and high ammonia concentrations can be lethal. Vermicomposting happens best when there is plenty of moisture in an aerobic environment at temperatures between 65-80 degrees.

To innoculate a new system where bedding is present, we suggest a minimum of one pound of earthworms per square foot of area. Where more information is desired, we recommend book #103 Worms Eat My Garbage for a thorough treatment of small-scale, home and school vermicomposting and book #101 Commercial Vermiculture for details about growing earthworms for profit in larger-scale systems.

The goal of vermicomposting (composting with earthworms) is to convert our garbage into the earthworm’s gold….castings. Worm castings can be added to potted plants, gardens, lawns, trees, bushes, and made into potting soil (use only 20% by volume in mixes). Liquid extracts called castings teas can be made and sprayed on plants for foliar feeding and used as a bio-insecticide or used as a soil drench. Unfortunately our space here does not permit a full description of the many exciting discoveries now being made in earthworm science and soil ecology, particularly in the area of horticulture and agriculture where plant growth trials and bio-pest control tests have proven nearly miraculous benefits of using earthworm castings.


African Nightcrawlers (Eudrilus Eugeniae) are great for bait, composting, and recycling. They are warm weather animals that do best when temperatures are between 65-80F. African Nightcrawlers can grow very large, often exceeding 9”. They are very prolific, are great composting worms, and produce wonderful organic fertilizer.

European Nightcrawlers (Eisenia Hortensis) are great for bait, composting, and recycling. They are tough, warm weather animals that do best when temperatures are between 60-70F. European Nightcrawlers can grow very large, often exceeding 8”. They are almost as prolific as African Nightcrawlers, are great composting worms, and produce wonderful organic fertilizer.