Cal-Mag: Calcium (Ca) & Magnesium (Mg)
and their cousin Iron (Fe)…
Calcium and magnesium often come together in a "Cal-Mag" supplement. These nutrients work together with iron in many plant processes, so iron is usually included in any Cal-Mag supplement.
Calcium, magnesium and iron are incredibly important to photosynthesis (making energy from light) and maintaining the structure of the plant. When things go wrong, you'll often see multiple deficiencies at the same time while plant growth slows to a halt.
Why do these three specific nutrients almost always come packaged together? Calcium, magnesium and iron are closely related when it comes to nutrient uptake. If there's a deficiency of one, it can trigger deficiencies of the others. So, iron is always provided in the right ratio of calcium-to- magnesium-to-iron, to help prevent an imbalance.
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Symptoms of Magnesium Deficiency
- Appears at the bottom of the plant on older growth (instead of on top like a calcium deficiency)
- Leaves become light green between the veins and may develop small brown spots
- Leaves eventually turn yellow and photosynthesis stops on the affected leaves
- If left unchecked, a magnesium deficiency slowly kills bottom leaves, with problems climbing up the plant as magnesium is transferred from older leaves to newer parts of the plant
- Leaves with a magnesium deficiency do not usually fall off the plant on their own (as they do with a nitrogen deficiency)
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