Shredded dull paper & junk mail, cardboard, coffee grounds (not too much), bit of sand for grit, and vegetable scraps make up the initial bedding material for the worm bins
Shown here is my set-up with the covers (no drilled holes) removed. There are holes drilled in the bottom and sides of all bins. I usually harvest castings from the lower bins, clean, then fill with new bedding. The top bins become the bottom bins. The worms in the bottom bins migrate to the top bins as vegetable scraps are added.
Rich castings in the bottom bin before harvesting. There will be only a few worms in the bottom since they have composted all the materials and migrated to the top.
Close-up of the castings before adding peat moss. Notice how moist and rich it is.
Harvesting the castings from three of the bottom bins gives me almost a wheelbarrow full of worm castings. I mix these castings with approximately half as much peat moss in order to dry the castings out and make them easier to add to the soil in my garden.
Because I waited too long to harvest castings from only the bottom bins, I have six full containers of casting/peat mixture ready for the garden. I harvested castings from all six bins (top and bottoms) in 3 hours. Each container initially held 35 lbs of cat litter.