Rhododendron vs Azalea: What’s the Difference?

Because their beautiful blooms are similar in size, color, and spring bloom time, many people don’t know the difference between rhododendrons and azaleas. Both also thrive in USDA zones 5 to 8, resulting in the plants often blooming at the same time in the same areas. As a result, this makes the plants even more difficult to identify. Let’s clarify and take a look at the differences.

Genus

Both rhododendrons and azaleas belong to the genus Rhododendron of the Ericaceae family. To make matter a bit more confusing, all azaleas are rhododendrons, but not all rhododendrons are azaleas. Think of it this way. In the same vein, all apple trees are fruit trees, but not all fruit trees are apple trees. In this case, the apple tree is an azalea and the fruit tree is a rhododendron.

The Size Difference Between Rhododendrons and Azaleas

Another difference between rhododendrons and azaleas is their size. Azaleas are small to medium sized shrubs with lots of branches. Rhododendrons tend to be larger plants with fewer and stronger branches. Both blooms and leaves also tend to be larger on rhododendrons.

Leaves

Another difference between these flowering shrubs is found in examining their leaves. The azalea leaves are smaller and narrower, and often have short hairs growing on the underside of their leaves. In contrast, Rhododendrons do not have these hairs and, instead, often have scaly dots on the underside of the leaves. The large and oval-shaped leaves are also leathery in appearance.

Shape of Blooms Difference Between Azaleas and Rhododendrons

One obvious difference between rhododendrons and azaleas is the shape of their blossoms. Azalea blooms are most often tubular or funnel shaped. Rhododendrons blooms are similar to the shape of a bell.

Stamens

Azaleas usually have 5 stamens, while rhododendrons have 10 stamens. If you really want to get into detail, the Sprigs and Twigs websites tells us that the azalea has 5 lobes and 1 stamen per lobe. In contrast, the rhododendron has 5 lobes and 2 stamen per lobe.

Deciduous versus Evergreen

Most azaleas are deciduous, which means they lose their leaves in the fall. One exception is the Japanese azalea that does not lose its leaves. In contrast, most rhododendrons are evergreen and retain their leaves during the winter.

Growing Conditions

Azaleas are less fussy than Rhododendrons. Like Rhododendrons, they need moist acidic soil. Unlike Rhododendrons, azaleas are more forgiving on soil quality and sun and wind exposure.

Rhododendrons require partial shade in humus-rich soil. They also do better in sheltered sites without much wind.

Does the Difference Between Rhododendrons and Azaleas Matter?

In three words – yes and no.

Yes, if it matters to you. If you are the type of person who loves knowing exactly what plants are in your garden, use these traits to identify that pretty pink flowering shrub in front of your house. Then, with that knowledge, optimize the growing conditions for your plant. Maybe move that rhododendron to a location where it gets more shelter from the sun and wind. Or, conversely, move your azaleas to a sunny location without worry.

No, if it doesn’t matter to you. If you enjoy your flowering shrub and don’t give a hoot what it is called, then more power to you. Enjoy the blooms and let others worry about stamens and genus.

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