When driving through a neighborhood from early spring through mid-summer, sometimes even late winter, the likelihood of seeing rhododendrons blooming is very high. Whether it is an older established neighborhood, or a relatively new one, there will probably be some rhododendrons in the plant palette.

And why shouldn’t there be? With their large colorful trusses of flowers, they can make quite a powerful statement in the garden.

The diversity of rhododendrons is vast. Not just their growing habits but their leaves, flowers, sun/shade locations, and fragrance can all be variable. There are, of course, rhododendrons with names that are popular and often even known to entry-level gardeners, probably because they have learned about a particular name from a neighbor. These well-known hybrid rhododendrons are good sellers at garden centers, especially when they are in bloom.

Another option

However, there is another classification of rhododendrons that is referred to as species rhododendrons. A quick botanical lesson reveals that the word ‘species’ refers to one plant or multiple plants. In botanical terminology, the word species is both singular and plural. Another quick fact is that all azaleas are technically rhododendrons. And as a final fact, there are native rhododendrons in the Pacific Northwest, primarily on the western slopes of the Cascades.

While there is certainly nothing wrong with planting a hybrid rhododendron, sometimes it can be interesting to get out of our comfort zone and plant something new. Species rhododendrons may not always have the spectacular flowers that many hybrids do, and while a species can give color interest with their flowers, they can also offer other features for garden interest such as colored or variegated foliage, indumentum (fine hairs), and variable growth habits.

Most garden centers carry predominately hybrid types, but there is a niche market for the species rhododendron, and it is surprising how many customers might gravitate toward a plant that was somewhat out of the norm.

Most, if not all, species rhododendrons are not grown in a large quantity by wholesale growers and thus, might be difficult to find. However, having a small display that is devoted to species could be a unique opportunity for additional sales resulting from word-of-mouth inspiration from other gardeners that this choice is available. The following species rhododendrons are some that offer some unique qualities and should be available.

Let’s start with Rhododendron macrophyllum, which is native from British Columbia through Northern California. The flower color of this plant ranges from rose to purple to shades of pink to white. It is the state flower of Washington. Mike Stewart, retired owner of Dover Nursery in Sandy, Oregon, and a rhododendron enthusiast, said, “This is a picture of Rhododendron macrophyllum and it has all three-color forms grafted on to one plant. The white form is one that my parents discovered in the 1960s and it is named ‘Clackamas White’. The pink bloom is the normal native pink in the Cascades. The red one was discovered in Northern California years ago. There is even color variation in the plant in our local environment.”

Rhododendron ponticum ‘Variegatum’ provides color in the garden all year with the creamy white edge around the margin of the leaves. In addition to the attractive foliage, the flowers are in trusses of lavender purple. There is a plant in my garden that is about 6 feet tall with an open growth pattern. Some of the leaves did get damaged with our January winter storm, but new growth is appearing, and it looks fine.

Both leaves and flower petals are very narrow on the Rhododendron linearifolium and it is probably one of the most unlikely looking rhododendrons that most people have seen. It will reach a height of about 3 feet and the flowers are so deeply divided that it is sometime referred to by the common name of spider azalea.  The narrow leaves tend to have a reddish cast in the winter. This would be a good specimen plant for a rock garden.

There are several different forms of Rhododendron yakushimanum with ‘Yaku Angel’ being a favorite in my garden. This group of rhododendrons comes from Yakushima Island, Japan. They seem to be quite winter hardy, have excellent foliage, and superb indumentum, and very showy flowers. ‘Yaku Angel’ has pink flower buds that open to white.

Not only does Rhododendron sinogrande have the largest leaves of any rhododendron, but it is also probably one of the most well-known of the genus. It is a magnificent plant in the garden with young new growth being a silvery gray. Older leaves have a silver-white indumentum underneath. The bell-shaped flowers are creamy white to pale yellow and very showy. This species requires some protection from the afternoon summer sun and extreme winter cold. Some plants were damaged in our January storm.

Rhododendron pachysanthum is an excellent foliage plant in all seasons and is often considered one of the best. The new leaf growth is a solid reddish brown with the underneath being a rusty brown. The new growth can almost be showier than the flowers. The bell-shaped flowers are light pink to white.    

The rhododendrons featured here are just the tip of the iceberg as to what is available. Any of these would be a good starter plant for a customer wanting to experiment and try something new. For a garden center selling this for the first time, or even a garden center that has some experience with species rhododendrons, signage would be very important.

Customers would need to be directed to this area with some information as to what a species rhododendron is and what makes them special. It can be a unique opportunity to gain new customers. Gardeners talk, and word would soon spread.

From the June 2024 issue of Digger magazine | Download PDF of article