With a 18-6-18 formulations, Triple Mag Iron features high amounts of magnesium, micronutrients and a sufficient amount of iron to supply nutrients for Petunias, Calibrachoa, Pansies, Vinca, Verbena and other plants that benefit from extra iron. To keep plants healthy, slow release calcium carbonate and magnesium help fuel photosynthesis and green leaf production. This product is excellent if you have high alkalinity irrigation water because it acidifies and also adds Mg to keep your Ca to Mg ratio in balance.