The nutrient Magnesium (Mg) can stimulate increased plant growth. Magnesium is an essential building block for chlorophyll and Magnesium deficiency may lead to a lower yield. Certain plants and cultivars (strains) of particular crops require magnesium due to their genetic growth patterns. 
 
House & Garden Nutrients MgO 8% Magnesium gives plants their fresh, healthy and green appearance. The nutrient is an important building block for chlorophyll and plays a key role in photosynthesis. It contributes to the strength of the tissue and the cell wall and is a building block for various enzymes. A lack of Magnesium will cause the leaf to turn yellow while the veins will stay green. The leaves will also fall earlier and have a reduced capacity for photosynthesis.