What Do Epsom Salts Do for the Root of a Flower?

Insufficient Magnesium

• The root system takes nutrients from the soil for the plant's use. If the soil is deficient in any one of them that is essential to the plant's life cycle, it must be supplemented with a balanced fertilizer or soil additive. In the case of insufficient magnesium, Epsom salts (magnesium sulfate) can provide magnesium for the roots to take up. Magnesium is an element that is part of chlorophyll, which is essential to photosynthesis, the energy-producing process that makes a plant grow. This is why one of the signs of insufficient magnesium is yellowing of the leaves between veins. Another sign is upward leaf curl. In advanced cases, the leaves turn brown and die.

Considerations

• Epsom salts are highly soluble. Too much water can leach away these salts, according to Dr. Linda Chalker-Scott, associate professor and horticulturist at Washington State University's Research and Extension Center. Application of Epsom salts will not help under leaching conditions. Sometimes it isn't the lack of nutrients in the soil, but their interaction with each other that deprives the roots of the nourishment the plant needs. For example, too much potassium may cause magnesium deficiency. In this case, reducing the potassium in the fertilizer used, or increasing the nitrogen, may be all that is needed to make enough naturally occurring magnesium available to the roots.

The Importance of Soil Testing

• Soil testing is the only sure way to know the nutrient values or the pH -- the acidity or alkalinity -- of the soil. Most university extension offices provide soil testing services. Plant roots cannot take up calcium, phosphorous and magnesium in highly acidic soils. Until a soil test can determine whether your soil is alkaline or acidic, or low in magnesium or too high in potassium, Epsom salts may not help.

Flowering

• Flowering trees or plants deficient in magnesium are stressed. Because of this, they are less able to take up other nutrients, or to utilize them. Although Epsom salts will relieve the deficiency, excessive amounts will not increase normal uptake. Chalker-Scott reports that there little evidence that Epsom salts applied to the soil or as a foliar spray can improve flower production. Though Epsom salts do correct plant and soil magnesium deficiencies, other claims about their benefits for already healthy plants are myths, according to Dr. Leonard Perry, professor at the University of Vermont Extension.