Worm castings (aka worm poop) is the goal of composting using worms. The microbes and worms in your bin transform “waste” products into castings that are full of nutrients and teeming with the biology your garden needs. Vermicomposting is the easiest way to compost food scraps, especially for city dwellers. I’ve been keeping worm bins for the past seven years, and this past summer, I screwed up. Learn from my mistakes as I reflect on what went wrong with my worm bin, why, and what I am making sure to do as I start over.