In Bloom: The Early-Blooming Rhododendron Behind The Waterfall

By Corinne Kennedy

The early-flowering rhododendron behind the waterfall (photo by Aleks Monk, 3/20/15)

In this dark time of year, I walk through my garden nearly every day, looking for even the smallest signs of new growth.  The showy flowers of hellebores and the delicate foliage of small species bulbs are starting to emerge.  Soon, I hope, the flower buds of early-blooming rhododendrons will begin to open.  Fortunately, rhododendrons and azaleas that bloom in late winter and early spring also grace our Seattle Japanese Garden.

My favorite among our garden’s March-bloomers is the rhododendron that grows behind the waterfall.  It has showy red flowers held in compact clusters, and beautiful bronzy bark.  The red color does have some pink in it -- but it’s closer to a true red than these photos indicate.  The original research for our garden’s Plant List booklet was done by Kathleen Smith over a period of many years.  She listed it as a “red rhododendron (unnamed)” that had been transplanted in 2001 from the greenbelt to its current location near the waterfall.  The original acquisition date, and when it was planted in the greenbelt, was unknown.  As a Garden Guide (member of Arboretum Unit 86) and one of seven Seattle Japanese Garden Plant Committee members, I hoped that our committee could find out more about this lovely shrub.  If so, our annual update of the garden’s Plant List would be more accurate, and we could introduce garden visitors to rhododendron species and hybrids with showy, early spring flowers.

Two of our garden’s past senior gardeners – Patty Ward and Jim Thomas -- contributed some clues.  The waterfall plant was Patty’s favorite rhododendron but she didn’t know its history, so she contacted Jim Thomas, who had served as senior gardener previously, beginning in the early 1990s.  He replied that he had planted it during that decade, having received it as an unnamed hybrid from one of our local rhododendron hybridizers.

Bristles on the stems & leaf stems of the waterfall rhododendron (photo by Aleks Monk)

Looking closely at our plant, and the photos committee member Aleks Monk had taken, I noted that it has bristles (fine hairs) on the leaf stems (petioles) and on the younger branches.  Because of these bristles and the plant’s early bloom time, it appeared to be one of the following two species:  Rhododendron barbatum or Rhododendron strigillosum – or perhaps a hybrid developed from one or both of them.  They are similar in several ways:  both bloom early with red flowers in a ball-shaped truss (instead of the higher, dome-shaped trusses of most rhododendron hybrids), both have bristles, and both mature to be large shrubs.  Our plant's leaves don't look exactly like the leaves of either species -- especially those of R. strigillosum.  However, species plants develop in the wild from seeds, and thus any one plant may differ significantly from another plant of the same species.  Ultimately, our plant’s trunk and stems most resemble those of R. barbatum.  Thus, I concluded that ours might be the species R. barbatum, or – more likely -- a hybrid with R. barbatum and/or R. strigillosum parentage.  However, we needed to consult an expert.

Kathy Lantz, the chairperson of the Plant Committee, agreed to follow up with Ray Larson, Curator of Living Collections at the University of Washington Botanic Gardens. After consulting with another expert, he replied:

“Richie Steffen, formerly the propagator for the Rhododendron Species Botanical Garden and for the past decade the manager of horticulture and then curator of the Elisabeth Miller Botanical Garden, thinks it is definitely a R. barbatum HYBRID, maybe with a little R. strigillosum ‘thrown in with a pink something.’

He also added: ‘Often, especially in the early days of rhodies, species were grown from seed and would result in hybrid seedlings being passed off as a species. It is most likely an unnamed seedling or received under a wrong species name.’

So I think that this is the best guess currently -- a Rhododendron barbatum hybrid.”

Flower truss of the waterfall rhododendron (photo by Aleks Monk)

Our waterfall rhododendron does, in fact, resemble descriptions of Rhododendron barbatum.  Native at high elevations in India, Nepal, Bhutan and Tibet, R. barbatum is a large evergreen shrub that’s hardy to about 5 degrees F.  It reaches about 4-5 feet tall in ten years -- eventually exceeding 20 feet in height.   With time, the bark on older stems matures to become a smooth, flaking, reddish-purple or bronze.   Leaf-stalks and young stems are covered in stiff bristles, hence the word barbatum, which means “bearded.”  Leaves are described as dark green, about 8 inches long, “elliptic-lanceolate” (that is, lance-shaped, but widest in the middle rather than at the ends) and puckered in texture.  The bright scarlet flowers are tubular to bell-shaped, and clustered in dense, round flower trusses.  They’re considered very early (opening from January to about March 15th) to early (opening between March 15th to April 15th).

For gardeners interested in adding early bloomers to their own gardens, it may be difficult to find R. barbatum or R. strigillosum at retail nurseries, but they are usually available online or at spring sales that feature unique plants from Pacific Northwest specialty growers.  Hybrids bred from R. barbatum are probably no longer available for purchase.  However, as noted earlier, R. strigillosum resembles R. barbatum in many ways, including flower color and early bloom time.  Several of its hybrids are excellent plants, and are usually available at retail nurseries or online.  They include the following -- all developed, as noted, by prominent Western Washington hybridizers.  They include very early, early and early-middle (April 15th to May 1st) bloomers.

‘Double Winner’ (early-middle; bright red flowers; H.L. Larson of Tacoma)

‘Etta Burrows’ (early; bright blood red flowers; H.L. Larson of Tacoma)

‘Peter Faulk’ (very early; vibrant red flowers; P. Faulk of Tacoma)

‘Grace Seabrook’ (early to early-middle; bright blood red flowers; Cecil S. Seabrook of Tacoma)

‘Taurus’ (early-middle, glowing red flowers; F.D. Mossman of Vancouver, WA)

When the Seattle Japanese Garden opens each year on March 1st, I make sure to visit the waterfall rhododendron, hoping that its flower buds have opened.  I love the beauty of its glowing red blooms and its coppery bark – and the promise of spring it brings to our garden.

Corinne Kennedy is a Garden Guide, frequent contributor to the Seattle Japanese Garden blog, and retired garden designer.