The ULTIMATE SOIL & CORK is a medium perfectly suited for both indoor and outdoor cultivation. It is enriched with organic nutrients. As a result, no addition of nutrients, depending on the crop and method of cultivation, is required during the first 4 to 6 weeks. For a higher yield, additional fertilization is recommended. Use only organic fertilizers such as Mills nutrients to prevent damage to the organic nutrients in the ultimate soil. Moreover, over-fertilization is practically ruled out using organic fertilizers.