This Is The Only Time It’s A Good Idea

Plants, like humans, need magnesium to function. "Magnesium is one of the essential macronutrients a plant needs for photosynthesis," Summer Rayne Oakes, the plant authority behind Plant One On Me, told mbg. "If you go back to the days of biology, you may remember that Mg is the central ion in chlorophyll, so plants need it to make food. It is also needed in RNA and DNA synthesis, binds to many important enzymes and assimilates phosphorus, which is another vital macronutrient. "The sulfur in Epson salt is also beneficial and helps plants produce important enzymes and proteins.

The healthiest, most resilient plants are those that get just the right amount of all essential nutrients – from magnesium and sulfur to nitrogen, phosphorus and potassium. This is why it is important to fertilize plants regularly, especially if their soil has known deficiencies.

Epsom salt is not a complete fertilizer. While it can increase the levels of magnesium and sulfur in the soil, it doesn't add any of the other nutrients a plant needs to grow strong.

The value of Epsom salt as a garden additive is slightly exaggerated, as is the case with coffee grounds. Unless your soil is magnesium and sulfur deficient, certified professional gardener and author Leslie F. Halleck, M.S. says the salts don't do too much. "And if you already have a fair amount of magnesium in the soil," adds Oakes, "it can create complications with the absorption of other nutrients."