Q. My neighbor puts epsom salts in the soil around his rose bushes instead of fertilizer. Is there any advantage to this?
A. Epsom salts have a long tradition of being used in the garden, especially in Europe, before commercial fertilizers became readily available. They are a fast-acting source for magnesium and sulfur. For soils on the alkaline side, the added sulfur is a benefit. Epsom salts, however, do not contain any of the three major components of most fertilizers—nitrogen, phosphorus or potassium—and therefore would not be a complete fertilizer for roses. If you choose a commercial product, one with a 10-10-10 or 10-15-10 ratio, apply it first when the leaves have opened; second, after the first flush of blooms; and finally, at the end of July.