Stewartstonian Azalea Shrubs

The evergreen choice for a red azalea

Stewartstonian azalea with its red flowers
David Beaulieu

Botanists refer to this plant as Rhododendron x Gable 'Stewartstonian.'  The "x" indicates that it is a hybrid plant, while the succeeding names are references to its developer (Joseph Gable) and where he lived (Stewartstown, PA), respectively.

Stewartstonian azaleas are broadleaf, evergreen shrubs. Beginners should take note that not all azaleas are evergreen. For example, plants in the Exbury group, which includes such standouts as 'Golden Oriole' and 'Gibraltar,' do drop their leaves for the winter.

What Stewartstonian Azaleas Look Like

The shrubs grow to be 4-5 feet tall, with a similar spread. These red azaleas are real show-stoppers when they bloom. Flowering begins in a zone-5 landscape, for example, in late April or early May. The flowers draw butterflies to your yard.

Flowers are wonderful, but the longer you garden and the more you pay attention to the changes in your plants as the four seasons unfold, the greater will grow your appreciation for attractive foliage. So let's take a look at the evolution of Stewartstonian azalea's leaves during the course of a year (again, using one located in zone 5 as an example):

By the time the new year rolls around, the shrub will have mahogany-colored leaves; the color is very dark. By March, red starts to work its way into the color mix, although the hues are still quite dark. In late June there is another color transformation: the summer sun puts the darkness to rout, and the leaves become medium-green.

Early August witnesses the first hints of the fall color to come, as a few leaves turn red. But one must categorize this shrub as a plant for late fall foliage: it is not until early November that red gains the upper hand. By late November the bush is totally red, except for the newest leaves, which are mahogany.

In December, the older, red leaves drop off, leaving the newer, mahogany ones in control. This final change brings us full circle, as those newer leaves will stay on through the winter (thus the "evergreen" status of this bush) and be the foliage that your Stewartstonian azalea starts out with next spring.

Growing Zones, Preferred Conditions, Care Tips

Stewartstonian azaleas can most easily be grown in growing zones 5-8.

Grow Stewartstonian azaleas in fertile, well-drained, acidic soil. Keep the soil evenly moist. These bushes like partial shade.

Applying mulch will help the soil retain the moisture it needs. Meanwhile, you can enrich the ground -- and improve its drainage at the same time-- by mixing in generous amounts of humus.

Prune after flowering to shape the bush, as needed. These are shrubs that flower on old wood.

Landscaping Uses

Azaleas are among the most popular spring flowers in North American landscaping. Red azaleas, in particular, such as Stewartstonian azaleas, are bona fide attention-grabbers in spring, and they should be granted a prominent location, where you can easily take in their beauty as you go about your daily chores. Nor do you have to worry that, after blooming is finished, the bush will just be "taking up space": Its attractive foliage warrants designating Stewartstonian azalea a four-season landscaping plant.

Some specific landscaping uses for this bush include:

Moreover, their shallow root systems make azaleas relatively safe plants for septic tank drain fields.

"Red Azaleas" in Two Senses

It is worth highlighting the fact that when we call Stewartstonian a "red azalea," the designation holds true in two senses:

  1. The shrub bears red flowers in spring.
  2. It also puts on a nice display of red fall foliage in the latter half of the autumn.

Plant Relatives, Additional Information

Azaleas are in the heath family. This means that they are related to, for example: