Magnesium is the fourth most abundant element in our bodies and essential to life. Magnesium is also essential to plants and is a key component of chlorophyll, the green pigment in plants. It is is part of the structure of both proteins and nucleic acids. Magnesium aids photosynthesis by activating carboxylase enzymes and it affects cell wall formation by activating peptidase enzymes.
Magnesium Deficiency in Plants
Magnesium deficiency is not uncommon in many soils and because magnesium is quite soluble it is easily leached from the soil. Also, many agricultural chemicals (such as ammonium nitrate), which are applied to crops, interfere with the uptake of magnesium by plants. The addition of calcium and potassium in excess of need can also deplete soils of magnesium. Some alkaline soils have a low pH and these at times will cause magnesium to be unavailable to the plants. Just as with calcium, high soil temperatures will affect the availability of magnesium to plants.
Magnesium deficiency in horticultural crops is manifested by a yellowing of leaves between the veins beginning at or near the tips and progressing inward toward the center vein until only a few vestiges of green remain. Such leaves are very brittle, the tips and margins tend to curl upward, and the plants are stunted in growth.
Adding Magnesium to Your Garden Plants and Soil
You can purchase Magnesium Sulfate from any garden center. Or you can make your own:
Mix 1 teaspoon epsom salts in 4 cups warm water, spray on plants and then again 10 days later.
On tomatoes, peppers and roses especially. Adds magnesium to soil.