Cal-Mag Growing Fertilizer Gallon - Prevents Blossom End Rot

In this review of the Cal-Mag Growing Fertilizer Gallon, the bottom line is simple: this fluid supplement is best for growers who need a reliable, bioavailable source of calcium and magnesium that also supplies a broader range of micronutrients. The product stands out because it pairs those primary elements with micro-chelation by fulvic acid, which reviewers and users say improves uptake and helps prevent common issues like blossom end rot and leaf yellowing. It is a practical choice for gardeners who want a single, easy-to-use additive that works across media and feeding systems.

Key Features

• Balanced Ca-Mg blend: Supplies calcium and magnesium to support strong stalk development and reduce blossom end rot in fruiting crops.
• Broad micronutrient profile: Includes Iron, Zinc, Boron, Copper, Manganese, Molybdenum, and Sulfur for overall plant vitality and to address subtle deficiencies.
• Bioactivated with fulvic acid: Micro-chelated formulation enhances nutrient absorption at the root, improving efficiency of each dose.
• Easy dosing options: Works as a feedwater additive or foliar spray with clear rates for grow and bloom phases to fit most feeding programs.
• Universal medium compatibility: Safe for soil, coco, peat, and hydroponic systems so it can follow plants through the entire cycle.

Who It's For

This product is aimed at hobby and serious gardeners who grow fruiting vegetables like tomatoes, peppers, and other nutrient-sensitive crops, and who want to prevent blossom end rot and yellowing leaves. It is also well suited for hydroponic growers who praised its performance in water-based systems and value a concentrated supplement that mixes readily into feedwater.

Growers who prefer single-element supplements or need an ultra-minimalist program may look elsewhere, and if a user requires a product certified for organic labeling they should confirm compatibility, since the formula is a bioactivated, micro-chelated nutrient blend rather than a straight organic amendment.

Pros & Cons

Pros

• Provides a balanced dose of calcium and magnesium that supports stalk strength and leaf health.
• Contains a wider array of micronutrients than many Cal-Mag products, helping overall plant vigor.
• Fulvic acid chelation improves uptake, which customers report as noticeable in growth and rot prevention.

Cons

• Label dosing requires care across grow and bloom phases, so beginners should follow instructions closely to avoid overuse.

Specifications

Product type	Cal-Mag growing fertilizer
Volume	1 gallon (128 oz)
Key nutrients	Calcium, Magnesium, plus Fe, Zn, B, Cu, Mn, Mo, S
Bioactivation	Micro-chelated with fulvic acid
Usage methods	Feedwater additive and foliar spray
Dosing (feedwater)	24 mL/gal grow, 35 mL/gal bloom
Dosing (foliar)	10-20 mL/gal up to 12 times weekly

Our Verdict

The Cal-Mag Growing Fertilizer Gallon is a practical, value-minded supplement for growers who need reliable calcium and magnesium with added micronutrients and improved uptake. It works across soil, coco, and hydroponic systems and is especially useful for preventing blossom end rot in fruiting crops, making it a good buy for gardeners who want performance without a complicated regimen.

Frequently Asked Questions

Can this be used in hydroponic systems?
Yes, the formula is compatible with hydroponics and reviewers specifically noted good results with hydroponic tomatoes.

What are the feedwater dosing rates?
Use 24 mL per gallon during the grow phase and 35 mL per gallon during the bloom phase as stated on the label.

Is foliar spraying an option?
Yes, it can be used as a foliar spray at 10-20 mL per gallon, up to 12 times weekly, for quicker nutrient uptake.