There are many articles on the internet that recommend using Epsom salt for gardening but the great majority of these articles are not based on science. We've done some research on this common practice and concluded that Epsom salts will add some magnesium and sulfur to the soil. If your soil is nutrient-poor, Epsom salts might do the trick, but gardening soil, in general, does not lack either of these nutrients. For fertilization, organic material and organic mulch are better options. When it comes to adding different substances to your gardening soil, it's best to be cautious and do some extra research, especially when it comes to things that are not intended for garden use.