Keep your plants productive and green with Cal-Mag, Emerald Harvest's calcium-magnesium supplement. Cal-Mag helps regulate plant growth and productivity and ensures essential chlorophyll levels when growing in coco coir and other media. Benefits Use Cal-Mag calcium-magnesium supplement to: Prevent calcium or magnesium deficiency in your garden Promotes chlorophyll production in your plants to keep them green and healthy Activate the enzymes that help your plants uptake nutrients.