Cal-Mag. By Emerald Harvest. 

There are some products that make a lot of noise, all glossy labels and bold promises, and then there are those that simply work. Quietly. Reliably. Relentlessly. Emerald Harvest Cal-Mag falls into the latter category. This isn't some gimmicky booster peddled by marketing types who’ve never touched a pH meter - this is the result of meticulous research by California-based growers who’ve spent years inside both micro-closets and mega-farms. And now, they’ve bottled up one of the most underrated yet utterly vital nutrient blends in indoor horticulture. It may look humble, but underestimate Emerald Harvest Cal-Mag at your peril.

Premium Ingredients.

At the heart of Emerald Harvest Cal-Mag lies the crucial pairing of calcium and magnesium - two secondary macronutrients that play an absolutely central role in plant physiology. Calcium strengthens cell walls and ensures proper division and elongation of cells. In short, it's the stuff that keeps your plants standing proud rather than wilting in misery. Magnesium, meanwhile, is the engine room of chlorophyll production. No magnesium, no chlorophyll. No chlorophyll, no photosynthesis. And without photosynthesis, well - you might as well switch the lights off and go home.

For All Water Types.

What makes Emerald Harvest Cal-Mag particularly important for indoor growers is its ability to fill the mineral void left behind by soft water. In areas with low dissolved mineral content, plants are often starved of calcium and magnesium from the outset. Even worse, these deficiencies can mimic other nutrient issues, leading to unnecessary guesswork and overcorrection. Symptoms like yellowing between veins or brown necrotic spots on the leaves are not just aesthetic disasters - they’re the start of a productivity collapse. This is where Emerald Harvest Cal-Mag steps in, correcting imbalances and keeping nutrient uptake on point.

Stronger, Faster Growth.

Even growers with hard water aren’t safe from cal-mag deficiencies, especially during bloom. That’s when potassium levels rise sharply - great for fruit and flower production, not so great for calcium and magnesium absorption. Potassium lockout is a very real thing, and it's intensified in coco coir, which naturally leaches potassium as it breaks down. If you're growing in coco and ignoring cal-mag, you're essentially building a house with no roof. Emerald Harvest Cal-Mag ensures your nutrient profile stays balanced, even in media that like to misbehave.

Made In California. 

More than just a patch for problems, Emerald Harvest Cal-Mag is a proactive performance booster. It enhances enzymatic activity and supports protein synthesis, driving stronger, faster growth. It doesn’t just react to stress - it builds a system capable of withstanding it. And because it’s engineered for compatibility, it plays well with every other product in the Emerald Harvest range. It’s not a flashy lead actor, but a supporting role so essential that nothing else works properly without it.

Essential for Professional Growers.

Available in four convenient sizes, from the compact 0.95 litre bottle to the grower’s favourite 9.46 litre jug, Emerald Harvest Cal-Mag is an investment in reliability. Use it from the moment your cuttings are rooted, right through to week six of flower, and you’ll notice tighter internodes, healthier leaves, and more vigorous growth across the board. It’s not a miracle - it’s just good science, applied brilliantly. If you’re serious about plant health and consistent harvests, Emerald Harvest Cal-Mag isn’t optional. It’s essential.