The three smaller rhododenrons in front of the large one by the windows have had their leaves yellowing and dropping. I put a question on the Asheville Plant People Facebook group and it was suggested that the new mulch we put down was probably leaching nitrogen from the soil. They suggested I pull the mulch away from the root area and spread Hollytone, but I had a large bag of Sta-Green Azalea/Camellia/Rhododendron food which has a good amount of nitrogen in it...and then put a lighter colored mulch on top. In the meantime I will water them regularly to wash in the fertilizer and watch to see the color improving.