When you vermicompost, you keep red wiggler worms or Eisenia fetida in a closed system, where they work to convert food scraps into worm manure with more minerals and nutrients than regular compost. The worms need bedding, such as soaked cardboard, to contain the pockets of food scraps, a moisture level of about 70 percent, darkness and a lack of nearby machinery or commotion. You can tackle vermicomposting projects tailored to the size of your worm herd, your experience with worm composting and comfort with tinkering.
A starter worm bin works well for home or classroom use. These can be as inexpensive as a salvaged bathtub or chest freezer, or you can pay $100 or more for well-rated plastic commercial models with stacking sections. You can also make your own worm bin out of a plastic storage tote or use salvaged plywood to construct a box with mesh-covered ventilation holes. Any shallow shape that allows oxygen to reach the contents with a lid to keep the bin dark tends to work acceptably. Place the bin in an area that stays between 55 and 77 degrees F, recommends biologist Rhonda Sherman at North Carolina State University.
Start instead with a flow-through bin if you are up for a more challenging project. Use a solid plastic trashcan or 55-gallon barrel. Cut a shallow window near the bottom of one side of the can. Create a grate out of conduit or reinforcing bars threaded above the window or salvage a barbecue grill to lie horizontally above the window. Scrape finished compost out of the bottom of the bin through the window while steadily adding food scraps and bedding at the top. This simplifies harvesting compared to the dump-and-sort method needed with basic bins.
Heating and Cooling System
Flow-through bins kept outside may need a little help to keep warm in the winter and cool in the summer. Wind about 20 feet of pond tubing around the perimeter of the inside of the trash can and thread the ends through holes drill in the sides near the top. Place an aquarium heater and a pond pump in an emptied and rinsed kitty litter bucket filled with water. Heat the water to 90 degrees and attach one end of the tubing to pump and submerge it. Guide the far end of the tubing into the bucket and let water circulate and return. Notch the lid of the kitty litter bucket to permit the pump's cord and the two tubing ends to enter the bucket and snap it on top. In the summer, remove the aquarium heater and replace it with a 1/2-gallon plastic milk container filled with frozen water and replace after thawing.