I got involved with vermicomposting almost 5 years ago and have used mainly black-and-white newspaper (which I knew to use a "safe" type of ink), egg cartons, and coir for bedding. I've been concerned because my source of "safe" color-free newspaper has disappeared and I didn't think an all-coir bin would be a good idea. I read your posting about using cardboard, which sounds like a wonderful idea and would solve my paper-shortage problem.

However, is any type of cardboard safe and healthy for composting worms? I've read that there are many types of cardboard -- is the type you use corrugated fiberboard that's used, for example, for shipping boxes? Should I use only plain cardboard with no print or glue in my worm bins, or is the ink and glue used on cardboard of no concern?

The thing I never like about newspaper (or other thin papers) is that they mat down and the worms have trouble getting to them. The corrugation in cardboard pretty much guarantees that there is no matting.

We use nearly any kind of cardboard we can find and we are not concerned with the glues. The one kind of cardboard I wouldn't use is the stuff that has colorful print on it. Diaper boxes, for example, are notoriously brightly colored and I'd never use those. Any brown cardboard is perfect.

If your city has a recycling center (nearly all do) they probably have as much brown cardboard as you could want. This is where we get most of our cardboard!

I used cardboard (not the "slick" glossy kind) and any (again not "slick" glossy advertising inserts) newspaper that has been put through a shredder. I've been using that along with shredded junk mail (no shiny). If you shred envelopes with a plastic window, you will find the shreds of plastic in castings as they won't touch them. Using a shredder keeps the bedding fluffy.