Cal-Mag is a liquid supplement that provides calcium, magnesium, and iron to plants. The micro-nutrients in Cal-Mag are primary ingredients required by all plants, but particularly those that bloom or produce fruits or vegetables. Both calcium and magnesium can also raise the pH level of the growing medium. Calcium aids in the growth of new cells. Calcium deficiency results in slower growth and fewer (or smaller) fruits, vegetables, or blooms. Magnesium plays a central role in the production of chlorophyll. In other words, magnesium assists plants to capture sunlight and convert it into energy for growth. Magnesium deficiency can result in slow or stunted growth.