BuildASoil Worm Casting Vermicompost 2 Gallon BagBuildASoil Worm Castings are simply the best bulk source of castings we have ever had the pleasure of working with, we often find living worms still inside the bulk totes. This stuff is black and rich with moist well screened castings. Enjoy! We go through large volumes so you know we always have fresh castings on hand and not last years left overs. Brew the best compost tea, use Earth Worm Castings.