What material do you recommend for the worm bedding in the Subpod?
The ideal material for worm bedding is coconut coir as it holds water very well to keep the worms moist and provides both bedding and food supply (carbon source) at the same time.
Coconut coir (shredded coconut husk) is best because it allows both moisture and oxygen to be retained in the system.
Dried bricks are easily purchased in the gardening section of stores such as Bunnings and Home Depot. If fine and coarse forms are available, choose the fine form. Follow the directions on the pack to pre-soak the coir with water until it has fully swelled and is uniformly damp, but not dripping wet. The worms can be directly added to this pre-moistened bedding.
To save money, shredded non-glossy paper or newspaper is another option, but not as ideal for initially setting up bedding as it clumps together when wet and the air that the worms breathe is not as uniformly distributed through the wet clumps of paper.
Cardboard can be used because it will maintain more air circulation through the system compared to paper due to its structure. You can use the cardboard from your Subpod packaging ;0