Botanicare Cal-Mag Plus Quart (12/Cs) Cal-Mag™ Plus is a highly fortified calcium, magnesium and iron plant supplement formulated to correct common deficiencies. Supplementing your preferred nutrient program with Cal-Mag™ Plus is strongly recommended when using reverse osmosis water and when growing in Coco Coir based medias to compensate for natural calcium draw. Cal-Mag™ Plus can also be applied as a foliar spray to ... This item is sold individually. — Ships from H: WA, CA, CO, MI, TN, PA, FL USA....more info.