JB - Horseshoe shared this with me about epsom salts when planting my first gardenia outside 4 years ago "As for the Epsom's salts, I use it sparingly, usually as a foliar spray to encourage flowering. However, if you are planning on using the sulphur to lower your pH plus using Epsom's directly in the soil they'll be competing with each other to do their job (Epsom's will tend to raise the pH slightly, thus my recommendation to use it more as a foliar spray, and do it when the plants are well on their way)."
I think after discussing this with several people. We felt that since I use potting soil with the added nutrients that it would not be wise to put the sale on them. That was a few months ago, so I need to go back and see if I am remembering correctly. Thanks so much for your help.