The Best Worms for Composting
Choosing the right worms is essential to successful worm composting. Learn what types of composting worms work best in your worm bin and why you can't use regular garden worms to recycle organic waste in this guide by Urban Worm Company Founder and worm expert Steve Churchill.
Contents
It’s common for the new vermicomposter to ask what kind of worms they should use in their worm bin. Aren’t they all the same? No. Not at all.
There are between 7000-9000 species of earthworms, but only about seven of them are any good as composting worms. Of those, only four are readily available in the US. We’ll cover those below.
But before we identify which species are suitable, it’s helpful to understand how earthworms can differ from one another.
Composting Worms Are In a Different Class
Earthworms fit into one of three classes based on their burrowing capabilities and the environments they inhabit: anecic, endogeic, and epigeic.
Anecic
Anecic worms are vertical and horizontal burrowers that come to the soil’s surface to forage for organic matter to take back their home, capable of pulling whole leaves into their tunnels. These tunnels can extend nine feet below the surface.
Anecic worms like the common nightcrawlers (Lumbricus terrestris) are excellent for your garden soil. They are strong enough to burrow in deep, compact soil, adding to the water distribution network beneath the surface. However, because they do not feed on the surface, they are not good composting worms.
Endogeic
Endogeic earthworms are horizontal “upper soil” burrowers who also rarely come to the surface, except to forage for food. They operate at shallower depths in the soil than anecic worms and form less stable burrows.
Because endogeic worms consume organic matter well below the surface, they are also not considered good composting worms.
Epigeic
Epigeic earthworms inhabit surface soils, leaf litter, manures, and other loosely-packed environments. They are not burrowers and would not survive in most garden soils, especially those heavy in clay.
But because they live on or near the surface and tend to swarm microbe-rich organic wastes, they are excellent composters. All composting worms types are epigeic. These are the worms you want to produce worm castings!
Which Worms Are Good for Vermicomposting?
Now that we know epigeic worms are the ones to look for, which species within this group should you choose?
Red Wiggler
The red wiggler (Eisenia fetida) is the most common and easily purchased composting worm in the US and Canada.
Like most epigeic worms, the red wiggler is smaller and less muscular, with a yellowish tail and banding throughout its body. As it reproduces quickly, operates in a wide range of temperatures (55-95°F), and is cheaper to purchase than other species, the red wiggler is the most appropriate choice for vermicomposters. Expect about 800-1000 worms per pound when purchasing red wigglers.
European Nightcrawler
The European nightcrawler (Dendrobaena hortensis) is the larger cousin of the red wiggler. It prefers a slightly cooler temperature so it should be considered a second choice, but it is also an effective composter.
While the Euro is large enough to double as a fishing worm, it also reproduces less quickly. Expect about 300-400 worms per pound when purchasing European nightcrawlers.
Indian or Malaysian Blue
The Indian blue (Perionyx excavatus) is often confused with the red wiggler and is sold as such to unsuspecting customers. While it is a voracious composting worm, it prefers warmer, tropical climates.
It is also sensitive to changes in barometric pressure. It’s not uncommon to see a mass escape (or attempted escape) in response to an approaching thunderstorm. If your worms freak out like this, the Urban Worm Bag’s design prevents wholesale jailbreaks through its zippered top and bottom.
Urban Worm Bag Eco: Made from Recycled Plastic Bottles!
Made with recycled plastic bottles in North America!
The Urban Worm Bag Eco is the newest in the line of Urban Worm Bags. It has identical form and function to the popular Urban Worm Bag Version 2.
It has the same dimensions, the same patented removable bottom, and the same coloring.
Most worm farmers in the US do not culture the Indian blue intentionally, so it is difficult to purchase them. But if you find a retailer who sells them, you can expect 800-1000 per pound.
African Nightcrawler
The African nightcrawler (Eudrilus eugeniae) is a large composting worm able to work its magic a little more deeply than other composting worms. Worm castings from African nightcrawlers are granular and considered attractive (insofar as worm poop can be considered ‘attractive’).
They require much warmer temperatures and may begin dying at 60°F, making them unsuitable in cooler regions without a climate-controlled environment.
As African nightcrawlers work different depths than red wigglers, some of my customers at the Urban Worm Company tell me they use both species to great effect. Expect about 300-400 worms per pound.
My Recommendation: Red Wigglers
The red wiggler is my top choice for a composting worm. It is a hardy worm and tolerant of the widest range of temperatures, especially in the cold. Some vermicomposters without good climate control have suffered extremely cold temperatures but are surprised to see thriving populations rebounding in the spring.
It’s also the easiest to purchase and is almost always cheaper than the other species. It has my thumbs up!
Just like with most things vermicomposting-related, there is no one right answer. Euros tend to work in cooler climates, African nightcrawlers need it to be warmer, and red wigglers tend to do well in all but the most extreme environments.
