FoxFarm® Cultivation Nation® Cal-Mag — 1 gal

Correct and Prevent Calcium and Magnesium Shortfalls During Fruiting and Flowering

FoxFarm Cultivation Nation Cal-Mag is a calcium and magnesium supplement formulated for the fruiting and flowering stages, when demand for these two secondary macronutrients rises sharply. In hydroponic, soil, or any other growing medium, Cal-Mag addresses deficiency symptoms before they cost quality or yield at a critical point in the crop cycle.

Reverse-osmosis and soft-water systems in particular tend to supply little natural calcium or magnesium, so growers using those water sources often need to supplement even when a base nutrient program otherwise looks complete.

Key Features & Benefits

• Targeted Calcium and Magnesium Supplementation: A concentrated, plant-available source of Ca and Mg for correcting or preventing deficiencies.
• Formulated for Fruiting and Flowering: Timed to meet the elevated calcium and magnesium demand of the reproductive growth phase.
• Compatible Across All Growing Systems: Works in hydroponic, soil, and soilless environments at both commercial and hobby scale.
• Liquid Concentrate: Fully soluble and mixes cleanly into nutrient reservoirs and irrigation water without sediment.
• Pairs With the Cultivation Nation System: Complements the Cultivation Nation Grow, Micro, and Bloom feeding program.

Who Should Use This

Growers running reverse-osmosis or soft-water systems, cultivators using coco coir, and anyone seeing early interveinal chlorosis, blossom end rot, or tip burn are the clearest fit for Cal-Mag, since a base nutrient formula alone often falls short of full Ca-Mg coverage under those conditions.

About FoxFarm

FoxFarm Soil & Fertilizer Company began in 1984 in Humboldt County, California, and has grown from those local roots into an internationally recognized supplier of plant nutrients and soil products.

Frequently Asked Questions

What are the signs of calcium or magnesium deficiency?

Calcium deficiency typically shows up as brown, crispy leaf tips, distorted new growth, and blossom end rot on fruiting plants. Magnesium deficiency appears as interveinal chlorosis, yellowing between the leaf veins, usually starting on older, lower leaves.

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 with reverse-osmosis water. It becomes most important during fruiting and flowering, when demand for these nutrients peaks.

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

Dosing depends on your base nutrient's existing calcium and magnesium content and your water source. Start at a lower rate and consult the FoxFarm feed chart, then adjust 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 at label rates is generally compatible with living soil programs and beneficial microbial inoculants.