It most likely needs the special fertilizer for that plant.........I found Vigoro at Walmart...but Lowe's Home Depot and other garden store have this feed for azalea, camellia & rhododendron 10-8-8 plus minors...promotes beautiful flowers & foliage, slow release nitrogen for extended feeding great for growing all acid loving plants including dogwood, evergreens, bougainvillea & hibicus. Detailed instructions are on the back of the 3.5 lb bag. Do not pile fertlizer next to trunk or at the base of the plant, water thoroughly after applying. Always brush or wash off fertilizer grannules off the leaves to prevent leaf injury. 1 cup = 1/2 lb 4 tbsp = 1/4 cup. This is for new plants and established plants. This can also be used in winter for blueberries. You might need to wait for spring to do your rhododendrons unless you live in a warmer area. Read the directions carefully and wear appropiate clothing and assessories.