GREEN PLANET - PRO CAL - 23LPro Cal is an excellent supplemental source of essential elements that plants require at all stages of growth. Green Planet formula provides readily available calcium and magnesium, as well as iron, nitrogen, boron, and zinc to ensure your plants do not come up short when they are ready for rapid growth. Plants undergo a large amount of stress and rapid assimilation of nutrients in their goal to build cell walls, produce chlorophyll, conduct