FoxFarm® Cultivation Nation® Cal-Mag — 1 gal

Correct and Prevent Calcium and Magnesium Deficiencies in Fruiting and Flowering Crops

FoxFarm® Cultivation Nation® Cal-Mag is a professional-strength calcium and magnesium supplement formulated specifically for use during fruiting and flowering — the growth stages when these critical secondary macronutrients are most in demand. Whether you grow in hydroponics, soil, or any other medium, Cal-Mag addresses and prevents the deficiency symptoms that can cost growers quality and yield at the most critical moment in the crop cycle.

Key Features & Benefits

• Targeted Calcium and Magnesium Supplementation: Delivers a concentrated, plant-available source of Ca and Mg in liquid form — ideal for rapidly correcting deficiencies and proactively preventing them from developing.
• Formulated for Fruiting and Flowering: Elevated calcium and magnesium demand during the reproductive phase makes supplementation especially critical as crops enter bud set and fruit development.
• Compatible Across All Growing Systems: Works in hydroponic, soil, and soilless growing environments — including both large-scale commercial and small hobby setups alike.
• Liquid Concentrate: Fully soluble and fast-acting — mixes easily into nutrient reservoirs and irrigation water without sediment or precipitate.
• Part of the Cultivation Nation Line: Pairs seamlessly with the Cultivation Nation 3-Part (Grow, Micro, Bloom) feeding program for a complete, integrated nutrient management system.

Who Should Use This

Cal-Mag is essential for growers running reverse osmosis water systems, soft water, or any growing program where calcium and magnesium are not sufficiently supplied through the base nutrient formula. It is particularly valuable in high-intensity indoor growing environments, in coco coir (which has a high cation exchange affinity for calcium), and for crops showing early signs of interveinal chlorosis, blossom end rot, or tip burn — classic indicators of Ca-Mg deficiency.

Compatibility

Cultivation Nation Cal-Mag is compatible with all major nutrient lines, including the Cultivation Nation Grow, Micro, and Bloom system. It is suitable for use in soil, soilless mixes, coco coir, rockwool, perlite, and all hydroponic delivery systems. When mixing your reservoir, add Cal-Mag before other nutrients to ensure proper dissolution and prevent precipitation.

Frequently Asked Questions

What are the signs of calcium or magnesium deficiency?

Calcium deficiency typically presents as brown, crispy leaf tips, distorted new growth, and blossom end rot in fruiting plants. Magnesium deficiency is characterized by interveinal chlorosis — yellowing between the leaf veins — starting on older, lower leaves. Both can appear together in plants grown in RO water or depleted media.

When should I start using Cal-Mag in my feeding program?

Cal-Mag can be introduced as early as the seedling or early vegetative stage as a preventive measure, particularly in RO-water systems. It becomes most critical during the fruiting and flowering stages when plant calcium and magnesium demand peaks.

How much Cal-Mag should I add to my nutrient solution?

Dosing varies based on your base nutrient’s existing calcium and magnesium content and your water source. Always consult the FoxFarm Cultivation Nation feed chart and start at a lower rate before adjusting based on plant response and ongoing EC and pH monitoring.

Is Cal-Mag safe to use with living soil and beneficial microorganisms?

Yes. Calcium and magnesium are essential minerals for both plant growth and soil biology. Cal-Mag supplementation at label rates is generally compatible with living soil programs and beneficial microbial inoculants.

Can I use Cal-Mag as a foliar spray?

Cal-Mag can be applied as a foliar feed for rapid correction of acute deficiency symptoms. Dilute appropriately, apply during lights-off or cooler parts of the day to prevent leaf burn, and avoid spraying during the late flowering stage to protect bud quality.