Mad Farmer Cal+Mag – 1 Quart

Mad Farmer Cal+Mag is a readily available Calcium and Magnesium supplement formulated to correct and prevent deficiencies across all growing media. It is especially useful when working with reverse osmosis water or coco coir, both of which are naturally low in these essential secondary nutrients. The formula contains no dyes and is compatible with all nutrient programs.

Mad Farmer Cal+Mag Specifications

The 1 Quart (32 fl oz) size is suited for home growers and small-scale operations. Below are the key product specifications derived from the manufacturer label and product documentation.

Specification	Value
Brand	Mad Farmer
SKU	MFCALMAG1QT
Container Size	1 Quart (32 fl oz)
Product Weight	0.49 lb (0.22 kg)
Active Ingredients	Calcium Nitrate, Magnesium Nitrate, Iron EDTA
Application Method	Nutrient solution or foliar spray
Dyes	None
Compatible Media	Hydroponics, coco coir, soil

Why Choose Mad Farmer Cal+Mag

Calcium and Magnesium deficiencies are among the most common issues growers encounter, particularly those using soft water, reverse osmosis systems, or calcium-hungry substrates like coco coir. Mad Farmer Cal+Mag is designed specifically to address these gaps.

• Prevents common deficiency disorders: The formula helps prevent blossom end rot and other deficiency-based plant disorders that arise when calcium and magnesium levels are inadequate in the root zone.
• Recommended for RO water growers: Reverse osmosis water strips minerals, leaving it essentially blank. Adding Cal+Mag restores the calcium and magnesium that plants depend on for cell wall development and chlorophyll production.
• Essential for coco coir grows: Coco coir is naturally low in calcium and magnesium and can actually bind these nutrients before plants access them. Supplementing with Cal+Mag at every feeding is the standard approach for coco growers.
• No dyes: The formula contains no dyes, which matters for growers monitoring runoff color or working in commercial settings where additives are tracked.
• Broad compatibility: Cal+Mag is formulated to work with all nutrient programs and growing media, so it adds to an existing feeding schedule without interference.
• Dual application flexibility: Can be added directly to nutrient solutions or applied as a foliar spray, giving growers options when rapid correction is needed.

The inclusion of Iron EDTA alongside calcium and magnesium is a practical formulation choice. Iron is a cofactor in chlorophyll synthesis, and its chelated (EDTA) form remains available across a wider pH range than iron salts, reducing the chance of lockout in slightly alkaline environments.

Best Uses for Mad Farmer Cal+Mag

Cal+Mag is most valuable in growing setups where the base water or substrate is deficient in calcium and magnesium. The following scenarios represent the product’s primary use cases.

• Reverse osmosis water systems: RO filtration removes nearly all dissolved minerals. Growers on RO water routinely add Cal+Mag at every feeding to re-introduce the secondary nutrients that plants need. The general-purpose dose of 5 mL per gallon is a common starting point.
• Coco coir grows: Coco has a natural cation exchange capacity that holds calcium and magnesium, making supplementation mandatory throughout the entire grow cycle — from seedling through harvest.
• Hydroponic reservoir management: In deep water culture, nutrient film technique, and other recirculating systems, maintaining consistent calcium and magnesium levels in the reservoir prevents deficiency symptoms from appearing mid-cycle.
• Correcting early blossom end rot signs: Calcium deficiency is the primary cause of blossom end rot in fruiting plants (tomatoes, peppers, cucumbers). Increasing Cal+Mag dose during the transition to bloom and flowering stages supports fruit set and development.
• Soil grows with soft tap water: Even in soil, regions with naturally soft water benefit from periodic Cal+Mag additions, particularly during heavy feeding periods when demand is high.
• Foliar correction of visible deficiencies: A rapid foliar spray at 5 mL per quart delivers calcium and magnesium directly through the leaf surface, which can address visible symptoms faster than root-zone application alone.

For growers looking to round out their supplement program, Earth Juice Hi-Brix Molasses is a complementary carbohydrate supplement used in organic feeding programs, and Advanced Nutrients Tarantula provides beneficial microbes that improve root-zone nutrient availability.

Mad Farmer Cal+Mag vs Similar Cal-Mag Supplements

Cal-Mag supplements vary primarily in their calcium-to-magnesium ratio, the form of iron included (chelated vs. sulfate), and whether the formula contains additional nitrogen. Mad Farmer Cal+Mag uses Calcium Nitrate and Magnesium Nitrate as its calcium and magnesium sources, which means it also delivers a small amount of nitrogen with each application. This is generally not a concern during vegetative and bloom stages, but growers in a strict late-flush phase should factor in the additional nitrogen.

The inclusion of Iron EDTA is a differentiating point. EDTA chelation keeps iron soluble and available at a broader pH range compared to non-chelated iron sulfate. This makes the formula more forgiving if reservoir pH drifts slightly above 6.5, a common situation in recirculating hydroponic systems.

The 1 Quart size is practical for small-scale and home growers who don’t want to commit to a gallon or larger drum before testing how the product performs in their specific system. Mad Farmer also offers Cal+Mag in larger sizes (1 gallon, 2.5 gallon, 6 gallon, 55 gallon) for commercial operations, making it scalable as output grows.

Compared to generic calcium and magnesium sulfate blends, the nitrate-based formula is typically faster to dissolve and less likely to cause clouding or precipitate in cold-water reservoirs.

Compatibility

Mad Farmer Cal+Mag is formulated to be compatible with all nutrient programs and growing mediums. According to the manufacturer, it can be used across the following setups without modification to the core feeding program:

• Growing media: Hydroponics (all systems), coco coir, soil, perlite, rockwool, and mixed media blends.
• Nutrient lines: Can be used alongside any existing base nutrient program. Add Cal+Mag to the reservoir or feed solution before adjusting pH to final target.
• Application styles: Suitable for both root-zone feeding (in-reservoir or direct pour) and foliar spray applications.
• Growth stages: Labeled for use from cuttings and seedlings through bloom and ripening, with dose rates scaled to match the plant’s demand at each stage.

When mixing nutrients, add Cal+Mag to plain water first, before adding other concentrated nutrient solutions. This prevents potential interaction between concentrated calcium and sulfate or phosphate salts that could cause precipitation. Always adjust pH after all nutrients are mixed.

Growers running microbial programs should note that the formula contains no registered pesticides or antimicrobial agents, making it compatible with beneficial bacteria and fungal inoculants. If you are using a microbial supplement such as Advanced Nutrients Tarantula, standard protocol applies: add Cal+Mag to water first, adjust pH, then add the microbial product last.

Dosing Guidelines

All dose rates below are taken directly from the manufacturer label for Mad Farmer Cal+Mag. Measure with a calibrated syringe or measuring cup. Always add Cal+Mag to water before other nutrients, then adjust pH to your target range.

Growth Stage	Dose (per gallon)	Approximate Volume
Cuttings / Seedlings	1–2 mL	1/4 – 1/2 tsp
General Purpose	5 mL	1 tsp
Vegetative Stage	5–10 mL	1 – 2 tsp
Transition to Bloom	10–15 mL	2 – 3 tsp
Blooming and Ripening	15 mL	3 tsp
Foliar Application	5 mL per quart of water	1 tsp per quart

For general-purpose use across all stages, the manufacturer recommends adding Cal+Mag to every feeding rather than on a rotation basis. This is especially relevant for coco coir growers, where calcium demand is constant regardless of growth phase.

When applying as a foliar spray, apply during lights-off or during low-temperature periods to minimize evaporation and reduce the chance of leaf burn. Spray until runoff and avoid applying to open flowers or fruit.

How to Use Mad Farmer Cal+Mag

1. Shake or stir the bottle before measuring. Settled particles are not typical for this liquid formula, but agitation ensures even concentration.
2. Fill your reservoir or mixing container with the target volume of water (plain tap water, RO water, or well water).
3. Measure the appropriate dose using a calibrated syringe or measuring spoon. Refer to the dosing table above for the correct rate based on growth stage.
4. Add Cal+Mag first, before any other concentrated nutrient solutions. This prevents precipitation that can occur when calcium-rich solutions contact phosphate- or sulfate-based nutrients directly.
5. Add remaining base nutrients and any other supplements in the order recommended by your nutrient line manufacturer.
6. Adjust pH to your target range after all nutrients are mixed. For hydroponics and coco coir, target 5.8–6.2. For soil, 6.0–6.5.
7. Check EC to confirm the final solution is within the appropriate range for your growth stage before feeding.
8. For foliar application: Mix 5 mL Cal+Mag per quart of clean water. Pour into a clean spray bottle or pump sprayer. Apply to both leaf surfaces during a low-light period. Do not apply to flowers or fruit.

Sources & Further Reading