Roots Organics CalMag is a pure and all natural blend of calcium, magnesium and sulfur to support plants during fast growth. By creating a product free of added nitrogen, phosphate, and potassium, Roots Organics give you control to supplement as needed without affecting primary fertility input ratios. Use in combination with high quality base fertilizers like Roots Organics Buddha Grow and Buddha Bloom. Free of added nitrogen, phosphate, and potassium Ideal for fast-growing and heavy feeding plants Derived from Kieserite, Gypsum