Nightcrawlers play an important role in the garden, aerating soil and releasing nutrients for plants to absorb. Adding a few to a terrarium may seem like a logical way to increase the health of the closed environment. However, nightcrawlers need space to burrow and a continuous supply of dead leaves or other organic material for food. Terrariums do not have the room for nightcrawlers to thrive and the dead material they need would make a terrarium unattractive.
Home Sweet Home
Although nightcrawlers are small creatures, they need a relatively large living space. Unlike some other types of worms, nightcrawlers build homes in the soil. They create burrows in the soil that can be 5 or 6 feet deep. Once this burrow is built, the nightcrawler leaves this burrow only to pull food down into the burrow or to eliminate waste. Terrariums are too shallow for a nightcrawler to create this home, and without it the nightcrawler cannot survive.
Nightcrawlers need their burrows for more than shelter. They pile leaves and other dead vegetation on top of the burrow. The nightcrawler slowly breaks up and pulls this material into the burrow. As it softens, the nightcrawler is able to consume it. The process also adds organic material to the soil. Because the soil in a terrarium is too shallow for a nightcrawler to build a burrow, it cannot benefit from the way nightcrawlers add organic material to the soil.
Small Critters, Big Appetites
Earthworms, including nightcrawlers, need to eat at least two thirds of their weight in dead plant material daily. Terrarium plants are not likely to produce that much debris, so plant material would need to be added to a terrarium continuously. The dead plant material cannot be incorporated into the terrarium soil, as nightcrawlers find food on the surface of soil. Adding the food for nightcrawlers would result in quite a large amount of decomposing material on the bottom of the terrarium. This material can encourage fungal infections in the warm, humid environment of the terrarium as well as being unattractive.
Although terrariums provide a controlled environment, keeping the temperature right for nightcrawlers may be difficult. Nightcrawlers need cool temperatures to survive. They prefer temperatures of around 68 degrees Fahrenheit and will stay in the sections of their burrows that keep this temperature consistently. Temperatures over 77 degrees Fahrenheit will harm nightcrawlers.
- Purdue University Extension: Earthworms and Crop Management
- University of Missouri Extension: Terrariums
- University of Nebraska-Lincoln: Vermicomposting: Composting with Worms
- Colorado State University Cooperative Extension: Earthworms: More than Fish Bait
- Clemson University Extension: Indoor Plants – Terrariums
- Colorado State University: Nightcrawler
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