Do Epsom Salts Help Plant Growth?

Plant Nutrients

• There are 16 nutrients that are essential for healthy plant growth. Nitrogen, phosphorous and potassium are known as "The Big Three" as plants use them in abundance. Of secondary importance are micronutrients such as calcium, magnesium, iron and boron. Though these elements are used in lesser quantity, they are still vital to the life of the plant. Epsom salts contain magnesium and are often used to alleviate magnesium deficiency in soils. Magnesium deficiency leads to a decline in chlorophyll production, which causes plants to bear thin, brittle, discolored leaves, rather than lush, green foliage.

Application

• Epsom salt is routinely scattered around the base of heavy-feeders, such as tomatoes, roses and azaleas -- or it is dissolved in water and sprayed on the foliage of houseplants and flowers for an easily accessed, foliar feeding. Though application rates vary from one type of plant to another, in general, the recommended rate is 1 tbsp. of Epsom salts for every foot of plant growth.

The Theory

• Epsom salts are water-soluble. Therefore, when subjected to rain or irrigation the granules dissolve, releasing magnesium into the soil where it is easily absorbed by the roots of nearby plants. The increase in magnesium results in a subsequent increase in chlorophyll, which leads to the development of healthy, green leaves -- and the growth of new shoots and stems.

The Reailty

• Epsom salts can help alleviate magnesium deficiency in garden soils but should be applied with caution. Bear in mind, plants need more than a single nutrient to be healthy. Also, magnesium deficiencies in the soil are not wide-spread and occur primarily in regions where acidic, sandy soils are commonplace -- as they do not retain water soluble nutrients well. Additionally, excessive quantities of magnesium can be just as harmful to plants as a deficiency, as the accumulation of salts in the soil can damage fragile root hairs and hinder plant growth.