The science is there for the human benefits of Epsom salts, but the plant ones? We asked some horticulture experts to get the scoop. The healthiest and most resilient plants are the ones that are getting just the right amount of all the essential nutrients—from magnesium and sulfur to nitrogen, phosphorous, and potassium. That’s why it’s important to fertilize plants regularly, especially if their soil has any known deficiencies. Epsom salt is not a complete fertilizer, so while it can boost the magnesium and sulfur count in soil, it won’t add any of those other nutrients a plant needs to grow strong. So, like coffee grounds, the value of Epsom salt as a garden additive has been slightly exaggerated. Unless your soil is deficient in magnesium and sulfur, certified professional horticulturist and author Leslie F. Halleck, M.S., says that the salts won’t do all that much. “And if you already have quite a bit of available magnesium in the soil,” Oakes adds, “then it can cause complications for the uptake of other nutrients.” However, the cohort of six gardeners noted that “it’s hard to find a direct link between a specific nutrient such as magnesium sulfate and increased yield or plant growth because of all the other variables in the soil, such as pH, calcium, and potassium content, and weather, that may affect the plants.” If you’re curious enough to give Epsom salts a try on your plants (they are, after all, really cheap and easy to use), here’s how to tell if your greenery could use the extra nutrients: Emma received her B.A. in Environmental Science & Policy with a specialty in environmental communications from Duke University. In addition to penning over 1,000 mbg articles on topics from the water crisis in California to the rise of urban beekeeping, her work has appeared on Grist, Bloomberg News, Bustle, and Forbes. She’s spoken about the intersection of self-care and sustainability on podcasts and live events alongside environmental thought leaders like Marci Zaroff, Gay Browne, and Summer Rayne Oakes.
