Magnesium is a mineral plants need to form chlorophyll, which gives plants their green color. Plants use chlorophyll to make food by using the sun’s rays. Magnesium strengthens cell walls, allowing the plant to receive necessary nutrients in the soil enabling it to grow.
Sulfate helps with production of chlorophyll, and allows plants to be infused with nutrients in the soil including nitrogen, phosphorus and potassium. Sulfate also helps to balance soil pH when it is very acidic.
Look at mature rose leaves to check for magnesium deficiencies in the soil. If the leaves are solid green, a magnesium deficiency is unlikely. Yellow leaves with green around the leaf veins creating an arrowheadlike shape in the middle indicate that there is a magnesium deficiency in the soil.
An old method of using Epsom salts with roses is measuring the rose bush’s height first, and then sprinkle 1 tablespoon of Epsom salts per foot of height into the soil around the plant’s base. Water it afterward to ensure incorporation into the soil. A 2-foot height bush would take 2 tablespoons of Epsom salt. Apply it in the spring and again in summer if a deficiency arises. Another method of application is dissolving Epsom salts in a gallon of water and applying to the soil around the rose.
Soils with a pH higher than 7.0 with high calcium and potassium levels usually have magnesium deficiencies. Test the soil. Epsom salts help give rose stems and leaves a healthy green color. The salt does not build up in the soil and therefore, making it safe for use. Epsom salts make rose bushes fuller and greener, and may help them produce more blooms.