A fridge is NO place for worms?! Or is it?
Turning a Fridge into a Worm Farm: Our Build with Wild Farm
When we agreed to install a worm farm at Wild Farm, the goal wasn’t just to build a random system, but to build one that worked for the farm.
At Terravore, we design systems around the realities of each site, from its space, materials, and budget. Sometimes that means repurposing what’s already there; other times, it means designing from scratch. The aim is always the same: creating regenerative, cradle-to-cradle systems that turn waste into a resource and improve over time.
The fridge worm farm is one example of that approach in practice.
Why a Fridge?
A fridge provides a solid base for vermicomposting because it is:
- Insulated, helping regulate temperature
- Durable, suitable for outdoor conditions
- Contained, reducing pest access
- Spacious, allowing effective layering.
Repurposing it also keeps the system aligned with circular principles.
The Build: A Practical Approach
We prioritised simplicity and ease of use in a working farm environment.
- Fridges need to be degassed. ( ⚠️This should always be done by a professional ⚠️)
1. Preparing the fridge
- Positioned for easy access in a well-shaded area to protect the worms from extreme temperatures.
- Remove internal fittings and seals, e.g. shelves.
- Close all holes that worms can climb into.
2. Passive airflow (no drilling)
- Seals removed
- The door was left slightly ajar.
This creates steady airflow without altering the structure unnecessarily.
- Gravel for drainage
3. Layered drainage System
The base was constructed using:
- Plastic vegetable crates for airflow space
- This combination helps prevent waterlogging while maintaining a stable habitat above.
- Burlap (hessian) as a breathable filter
4. Bedding and worms
- We added Compost aged 1 year from Wild Farms bale.
- Moisture balanced carefully
5. Feeding approach
We used materials already available on the farm:
- Green leaf at the top of carrots
- Kale leaves and surplus greens
- General plant-based waste
- Introduced Eisenia fetida
- Nitrogen-rich greens
- Carbon-rich dry materials
We added 4kg of Eisenia fetida, and there is more than enough waste available for the worms.
How the System Works
The system follows a simple cycle:
- Food waste is added in layers.
- Oyster Shells/ Eggshells aid in worm digestion
- Worms and microbes break it down.
- Moisture moves through the base layers.
- Finished Compost accumulates as worm castings.
- We finished the fridge with a carbon (cardboard) layer on top, helping reduce pests, manage odours, and maintain balance.
The output is a stable, nutrient-rich material that supports soil health. Wild Farm will use the on-site vermicompost to improve soil structure and, hopefully, increase vegetable growth, as evidenced by reviews of the farm-to-“fork” part of the operation.
What We’re Testing (and Why It Matters)
This is a live system designed to be practical and manageable within a working farm environment.
We are observing how it performs over time, focusing on:
- The integration of the system into their farming practice
- Moisture balance within the layered base
- Worm behaviour in a larger enclosed system
- Processing speed of organic waste
- Quality of the final Compost
Early on, one noticeable outcome was how effective the carbon layer was at keeping flies down, even within the first few feeding cycles. The passive airflow also appears to be maintaining oxygen levels without drying out the system. These are early observations, but they help guide how we may refine the system.
What Happens Next
We will continue monitoring the system with Wild Farm, with a more structured review planned over the coming year.
This will focus on:
- Worm health and retention
- Drainage performance
- Consistency of compost output
Any adjustments will be based on real use and long-term performance.
Key Differences
This build intentionally departs from typical designs:
- No drilled ventilation holes
- Airflow is managed through an open-door system.
- A layered drainage base using gravel, crates, and burlap
The drainage system, in particular, is something we will continue to assess and refine. As the Wild Farm team becomes more experienced with worm care, we may eventually remove the drainage layer, as they will have learned how to maintain optimal conditions without it.
Reflection
This project highlights a simple principle: effective systems don’t need to be complex; they need to be appropriate.
Whether repurposed or built from scratch, the goal is to create systems that fit their environment, use available resources wisely, and improve over time.
For those looking to try something similar, start with what you have, keep it simple, and allow the system to develop through observation.