VermiWorm™ Premium Worm Castings are created by red wigglers; these are pure eisenia fetida castings. They are farmed organically in California by agriculturists who truly care about what they do. VermiWorms™ are fed a specific diet of organic matter containing no manures or chemicals. VermiWorm™ can be used as a soil conditioner for any natural or potting soil and as a primary ingredient in compost tea.