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, we give you control to supplement as needed without affecting primary fertility input ratios. Roots Organics CalMag is ideal for fast-growing and heavy feeding plants. Use in combination with high quality base fertilizers like Roots Organics Buddha Grow and Buddha Bloom.