Why can’t I just use my backyard garden worms?
Well, you could…but you probably won’t have enough success to want to keep doing it.
Not all worms are created equal
There are over 9,000 species of earthworms on the planet, but there are only seven that would be considered suitable for vermicomposting (composting with vermi: worms). Of those seven, Eisenia fetida (eye-SEN-ee-a FEH-tid-a) is used in approximately 85% of commercial worm farms worldwide.1
Eisenia fetida is more commonly referred to as the “red wiggler.” Red wiggler is simply a nickname, and is often also applied to another vermicomposting worm: Eisenia andrei. The two worms are very similar in appearance, biology, and habits. They are very difficult to tell apart without a microscope and a lot of experience. Many commercial farms have been found to have a mix of E. fetida and E. andrei happily cohabitating and often sold under the single title of Red Wiggler.
Deep Divers vs. S%!# Eaters
If you grew up in the 90s like I did, your knowledge of earthworms was gained by playing video games like Earthworm Jim and Worms: Armageddon. If your resources were similar to mine, the following statement may blow your mind: not all earthworms eat earth.
All worms can be split into three groups:
- Anecic: from Greek “out of the earth”
- Endogeic: from Greek “within the earth”
- Epigeic: from Greek “upon the earth”
Red Wigglers are epigeic mound-dwellers, living upon the earth. They are earthworms that DO NOT live in earth. They DO NOT eat earth. They are happiest in a big ol’ pile of manure…which they also eat. On some continents, they’re known as dung worms. They eat much more than just poop, they eat anything that’s decomposing on the surface of the ground. This matter is called detritus, or litter. This is why they’ll happily consume your leftover food waste, and also why you don’t need to add soil to your vermicompost bins. Since Red Wigglers don’t burrow, they can’t escape the harsh winters. They die off in the winter, but they leave their cocoons behind to re-establish their population in the spring.
A quick rabbit trail: The fact that Red Wigglers don’t live in or eat soil is why I don’t recommend putting them in your garden. They are weaklings that can’t handle moving through thick soil. Plus, they’ll starve in your soil. Unless you’re consistently adding some sort of litter/waste/cured manure, Red Wigglers will eventually starve and die in your garden soil.
The big fat worms in your garden are from the deep-diving anecic group. This group has different types of nightcrawlers. In the Regina area, they are most likely Lumbricus terrestris and known as Canadian Nightcrawlers, Dew Worms, or Granddaddies. Anecic worms live deep enough underground that they are able to overwinter in harsh Canadian winters. Unfortunately , they deposit most of their poop (castings) in those deep burrows: not very convenient if you’re a gardener. The fact that they burrow deeply makes it difficult to raise them in bins for home composting. I’ve heard of people doing it though!
Both types of worms are helpful for gardening through soil aeration and water penetration, but Red Wigglers (and other epigiec varities of worms) will allow you to harvest castings which have many uses in agriculture and home gardening.
1 Sherman, Rhonda. The Worm Farmer’s Handbook. 2018