Calcium and magnesium: the overlooked macronutrients

Calcium and magnesium are essential nutrients that are often overlooked:

**Calcium (Ca) - Functions:**

*Structural role:*

- Cell wall stability and strength

- Maintain membrane integrity

- Promote root development

- Stalk reinforcement

- Resistance to pathogens

*Physiological functions:*

- Enzyme activation

- Protein synthesis

- Hormone regulation

- Metabolic processes

- Stress signalling

*Calcium in cannabis:*

- Requires 150-200 ppm in nutrient solution

- pH-dependent availability

- Important for cell division

- Structure for heavy flowers

- Preventive against crack stem

**Magnesium (Mg) - Functions:**

*Chlorophyll centre:*

- Core of the chlorophyll molecule

- Photosynthesis efficiency

- Light-energy conversion

- Green colour preservation

- Primary photosystem function

*Enzymatic role:*

- Activates over 300 enzymes

- ATP formation and utilisation

- Protein synthesis

- DNA/RNA replication

- Metabolic pathway activation

*Magnesium in cannabis:*

- 50-75 ppm optimal

- Mobile nutrient (from old to new)

- Critical for flower development

- Energy transfer important

- Stress resistance

**Recognise Cal-Mag deficiency:**

*Calcium deficiency symptoms:*

- Brown spots on leaves

- Leaf margin necrosis

- Weak, hollow stems

- Delayed root growth

- Susceptibility to flower rot

*Magnesium deficiency symptoms:*

- Intermittent chlorosis (yellow leaves, green veins)

- Starts with older leaves

- Rust-coloured spots

- Leaf curling

- Reduced photosynthesis

*Combined Cal-Mag deficiency:*

- Common in coco substrate

- Soft water problems

- LED light exacerbates symptoms

- Rapid progression

- Multiple symptoms simultaneously

**Causes of Cal-Mag deficiencies:**

*Substrate-related causes:*

- Coco binds calcium/magnesium

- Coco not pre-treated

- RO water without minerals

- Excessive potassium fertilisation

- pH values outside 6.0-7.0

*Environmental factors:*

- LED lighting increases demand

- High light intensity

- Low humidity

- Extreme temperatures

- Stressful situations

*Antagonistic interactions:*

- Excess potassium blocks calcium

- Ammonium-nitrogen inhibits calcium

- Excess phosphorus reduces magnesium

- Sodium competes with calcium

- Unbalanced nutrition

**Cal-Mag sources and supplements:**

*Commercial Cal-Mag products:*

- Liquid Cal-Mag (mostly 2-0-0)

- Cal-Mag with iron

- Organic Cal-Mag options

- Instant soluble powders

- Strain-specific formulations

*DIY Cal-Mag Solutions:*

- Calcium nitrate + magnesium sulphate

- Dolomite lime for long term

- Gypsum (calcium sulphate)

- Epsom salt (magnesium sulphate)

- Organic bone meal

*Dosage Guidelines:*

- Standard: 5ml/L Cal-Mag Supplement

- Coco: 3-5ml/L throughout

- RO water: Always add Cal-Mag

- LED-Grows: 20-30% more

- Strain-dependent adjustment

**Application and timing:**

*Preventive application:*

- From the beginning of the vegetative phase

- With each nutrient dose

- Particularly critical in Coco

- LED setups require more

- Continuous throughout lifecycle

*Corrective Measures:*