Epsom Salt or Magnesium Sulfate is a chemical compound made up of magnesium, sulfur, and oxygen. It gets its name from the town of Epsom in Surrey, England, where it was originally discovered.
Epsom salt is a popular remedy for many ailments. People use it to ease health problems, such as muscle soreness and stress. It has many health benefits but I’m not going to talk about its health benefits here but its role in the garden.
I remember the first time I bought 5 boxes of the quart size of Epsom Salt at the drug store. People looked at me with that questioning look - “What is wrong with you?”. I had to tell them that I used them to fertilize my roses. “Really?” I had to show them the label where it said good for plant growth.
Epsom Salt is an important part of the rose diet. It is an essential element for plant growth and since its availability is limited in our soils, we have to supplement it. Without magnesium in the soil, the plant roots can’t take up available calcium and potassium. It is absorbed by the root hairs and located for the most part in the leaves.
Magnesium is a photosynthetic pigment which causes water and carbon dioxide to react in the presence of sunlight to form starch, followed by many other nutrient building reactions. It keeps the nitrogen in the lower leaves and forms the chlorophyll molecule, the most important molecule in the formation and development of plant life.
I usually put in a cupful of Epsom salt in the hole for big roses and ½ cup for mini roses when I plant them. I also sprinkle them around the garden in the spring and another application in the fall. Water them after each application or do it before it rains. Epsom salt will help keep green foliage on your roses and encourage new basal breaks. It works the same way with all your other plants.
Nowadays, they sell several Epsom salt brands at gardening centers. I prefer the drug store variety because I know it is the real thing.