Keep your plants productive & green with cal-mag, a calcium & magnesium Supplement from Emerald harvest. Containing top-quality ingredients, cal-mag is designed to nourish crops with extra calcium & magnesium & create the right conditions for abundant flowering & a heavy yield. This is especially important when growing in some media, such as coco coir, but any garden can benefit. Use cal-mag as a Supplement to a base nutrient series for guaranteed professional results.