The yellow leaves of Rhododendron may be caused by too strong alkaline soil. At this time, it should be replaced with slightly acidic culture soil, or poured with ferrous sulfate solution every month to acidify its flower soil. It can also be caused by too much light. At this time, move it to a place with shade, cut off the yellow leaves, and wait for it to grow new leaves. It can also be caused by over watering. At this time, the rotten roots and yellow leaves on the plant should be cut off, and then it should be planted in the new soil for maintenance.