And azaleas are mostly deciduous with a softer leave structure. Introduction to rhododendrons and azaleas. Azalea & Rhododendron. Rhododendrons are generally evergreen with glossy dark leaves. Dig a hole in the soil near the plant stem to see whether excess water is pooling. I increased the watering to compensate for the hotter temps and a about a week or two later the older growth leaves died. To distinguish between the two, it is much easier to look at the flower. But, there are some deciduous rhododendrons and a few evergreen azaleas. How can you tell if an azalea is over-watered? So how can you tell the difference between rhododendrons or azaleas? The Difference Between Azaleas and Rhododendrons. There are more than 900 species in the Rhododendron genus, which vary greatly. 11 years ago. You may be interested in joining the American Rhododendron Society, which runs a database with information on more than 2,000 rhododendrons and azaleas.On an annual basis, the society selects a number of rhododendrons to be awarded the Rhododendron of … It would take a whole book to understand this wide world! Many people get these two plants confused. Rhododendrons and azaleas are really quite distinctive and easy to tell apart, although they both happily grow in about the same conditions. Azaleas are in the genus Rhododendron. Prune deciduous azaleas while they are dormant and leafless. Although considered distinctly different by many horticulturalists and gardeners, botanists place both rhododendrons and azaleas in the genus Rhododendron.Linnaeus classified azaleas separately, as genus Azalea, but subsequent generations of botanists have decided that the two are closely enough related that they should share a classification. Rhododendron leaf wilt, often interpreted as a sign of thirst, can conversely indicate that the plant is drowning. You don't have to prune azaleas as carefully as you do rhododendrons―the leaves are fairly evenly spaced along the branches, with a bud at base of each leaf, so new growth will sprout from almost anywhere you … I have a few shade azaleas that I planted in March which have been doing very well until a few weeks ago when it got hot. The thing to remember is all azaleas are rhododendrons but not all rhododendrons are Azaleas. bamboo_ca.