Epsom salt consists simply of magnesium sulfate. It is often used to ease the pain of sore or tired feet in a foot bath, but it can also be used in the garden to enhance performance of fruit. It is reported to improve the growth of tomatoes and stop blossom end rot that can totally rot a tomato.
Epsom salt provides a good source of magnesium. Magnesium aids in chlorophyll production in plants. It is important because it enhances photosynthesis, or the manner in which plants breathe. They breathe in carbon dioxide and put out oxygen. Magnesium is usually found in the soil and is often included in many fertilizers.
Sulfur is a component in Epsom salt. Sulfur gives plants protein and other enzymes necessary for them to grow strong. Roots grow better with the benefit of sulfur and it helps plants endure colder temperatures. Sulfur is naturally delivered to plants through rain, but often they need a little boost.
Yellowing leaves starting at the bottom and progressing to the top are one sign of a magnesium deficiency. Blossom end rot is also a sign. This is when the tomato blossom causes a large black spot on the very bottom of the fruit that gets bigger and bigger as the tomato grows. Eventually it will rot all the way through the tomato, rendering it useless.
How to Use
Place a few granules of Epsom salt in the hole before planting the tomato plant. Once blossoms appear on the plant, sprinkle 1 tbsp. Epsom salt per foot of plant height around the base of the stem. Scratch it into the soil and water well. A plant 2 feet high should be treated with 2 tbsp. Epsom salt, while a plant less than 12 inches high will do with 1 tbsp. Apply every other week.
Dissolve 1 tbsp. Epsom salt in 1 gallon of water. Place some in a spray bottle and use this to spray on the fruit and foliage. This will keep the foliage green and also increase the thickness of the walls of the fruit, making for a delicious tomato. There is no real scientific evidence that Epsom salt works on tomatoes, but many gardeners have been using the substance with both tomatoes and peppers for years with great success.