Magnesium is essential for photosynthesis in that it is an important element in chlorophyll production. Deficiency symptoms generally become evident in older leaves first and are indicated by a yellowing of leaf tissue between the veins, sometimes accompanied by orange tints. Affected plants deteriorate rapidly, loosing leaves and eventually dying. If you suspect a magnesium deficiency, it is a good idea to conduct a pH test on the soil, as it can be a symptom of too alkaline conditions. Application Rate: Dissolve 10 grams (approx. 2 teaspoons) in each litre of water and apply liberally over soil around the root system. For plants showing severe deficiency symptoms, repeat this application every 4 weeks until symptoms ease.