Roots Organics Big Worm provides your plants with the additional nutrient they crave most; worm castings Roots Organics takes special pride in caring for their worms, which are fed an unparalleled blend of organic compost, rock dust, and kelp for exceptional quality castings. This is then added to premium soil mixture, enhancing it with Nitrogen, small amounts of Phosphorus and Potassium, naturally occurring micronutrients, minerals and beneficial bacteria. premium Worm Castings is a distinctive natural soil amendment. Overall this soil is gauranteed to give your plants just what they need. Quanity: 1 cubic ft.