Is Epsom Salt Good for Growing Tomatoes?

Epsom Salts

• Epsom salt is a highly water soluble form of the mineral element magnesium. Epsom salt is primarily a pure crystal form of magnesium sulfate. One of the earliest accounts of finding underground supplies of magnesium sulfate occurred in Epsom, England, during the Renaissance. This location name became attached to the crystal compound, and calling it salt refers to its general physical similarity to table salt (sodium chloride). When used in the garden soil, magnesium sulfate provides magnesium -- the central atom in a green chlorophyll pigment molecule -- for absorption and use by plants.

Growing Tomatoes

• Gardeners eagerly monitor and wait for their tomato plants to grow in the fertile garden soil and sunny, warm conditions. Numerous pests, diseases and ailments can strike a tomato plant, resulting in wilting, yellowing leaves, dropping flowers or no fruits. American gardening folklore often blindly recommends applying Epsom salt to tomatoes. However, Epsom salt is not necessary for healthy tomato plants if the garden soil already is fertile, slightly acidic in pH and magnesium is not deficient.

Use on Tomatoes

• Because Epsom salt is water soluble and leaches quickly through soil, it's difficult to harm tomato plants with an application of a solution comprising 1 tsp. Epsom salt in a gallon of water every month. The practice may be unnecessary, however. Magnesium deficiencies occur in tomatoes when the garden soil is neutral to alkaline in pH, overly rich in potassium or the native soil naturally contains a very low amount of magnesium. If your garden soil is already fertile and rich in organic matter, chances are magnesium occurs in ample amounts without using Epsom salts. Only with a soil test can you truly learn if your garden soil does not provide magnesium in appropriate levels to your tomato plants.

Insight

• No doubt, the limited use of Epsom salts as a light fertilizer for tomatoes can be beneficial, but the need or efficacy is likely more based in myth, according to the Washington State University Puyallup Research and Extension Center. Applying Epsom salts to tomatoes that grow in known magnesium-deficient soil does increase plant health, but has no effect on yield of fruits. Therefore, arbitrarily adding epsom salt can lead to contamination of the soil, nutrient imbalances and a false sense of security. Magnesium deficiency in tomato creates symptoms that look exactly like other nutrient deficiencies, disease or insect problems. Find the real reason for the malady and do not just blindly apply more Epsom salt.