Great Plant Picks 2005: Rhododendrons

 In the first installment of the Great Plant Picks for 2005, appearing in the last issue of Pacific Horticulture, Carolyn Jones presented the trees, shrubs, conifers, vines, and perennials that have been recommended by the GPP committee. In this issue, Rick Peterson reviews the list of rhododendrons receiving the nod from the Rhododendron Advisory Group. Given the number of cultivars available, narrowing down the “best for the Northwest” list was no small assignment.

In horticultural circles today, form and texture are much ballyhooed in landscape design; yet, flower color will always have a powerful allure—much like the mythical Siren’s song. Among woody ornamental shrubs, who can resist the dazzling blossoms of roses, camellias, forsythia, hydrangeas, and rhododendrons. Indeed, rhododendrons are one of the most popular shrubs grown in Pacific Northwest gardens, where the generally mild climate favors a wide range of species and cultivars.

With thousands of rhododendron hybrids to choose from, the task of making a selection can be overwhelming. The Great Plant Picks team formed a Rhododendron Advisory Group to sort through the vast array and recommend a selection of outstanding rhododendrons for gardeners in the maritime Northwest.

The group’s first efforts resulted in the creation of a rainbow collection of hybrid rhododendrons featuring pink, yellow, red, purple, and bicolor flowers. Gardeners can be confident when choosing any of the following selections—these are the best of the best!

Rhododendron ‘Queen Alice’. Photograph by Richie Steffen

Rhododendron ‘Queen Alice’. Photograph by Richie Steffen

Pinks to Start the Season

After enduring months of short days and slate gray skies throughout the Northwest, the yearning for color in the garden becomes intense. In midwinter, few shrubs rival the petite domed, pale pink trusses found on Rhododendron ‘Christmas Cheer’ and R. ‘Rosa Mundi’. These two almost indistinguishable cultivars may open in late January but, more commonly, flower in February or early March. With either, one is assured that spring and rainbows are not far off. They belong to a group of ten exceptional pink hybrid rhododendrons chosen by the Rhododendron Advisory Group.

Rhododendron ‘Mrs Furnivall’ is a stunning, mid-spring showpiece of light pink flowers, each with a prominent crimson flair. Among the other cultivars in the pink collection that flower in early May are R. ‘Dreamland’ (pastel pink), ‘Mardi Gras’ (white blushed pink), ‘Noble Mountain’ (pink), and ‘Queen Alice’, the latter with richly colored flowers of bright rose pink opening from cherry red buds. The remainder flower later in May: R. ‘Trail Blazer’ with pink blossoms and a cranberry blotch, ‘Very Berry’ with large conical trusses of rosy red, and ‘Janet Blair’, which is embellished with golden bronze rays on light pink petals.

Rhododendron ‘Horizon Monarch’.  Photograph by Al Dodson

Rhododendron ‘Horizon Monarch’. Photograph by Al Dodson

Yellow for Warmth

Yellow-flowered rhododendrons add warmth to the suffused greens of the woodland garden. Rhododendron ‘Lemon Dream’ is a superb cultivar with abundant, soft lemon yellow flowers that are sometimes double. Other midseason selections are R. ‘Horizon Monarch’ with scarlet buds opening to large, pale, green yellow flowers, ‘Odee Wright’ with deep clear yellow blossoms, and ‘Nancy Evans’; the last has the most complex coloring with orange red buds opening to amber yellow flowers, becoming a rich golden yellow while retaining some of the amber hues on the outer edge. Rounding out the group is R. ‘Capistrano’ with blossoms of light greenish yellow that appear in late midseason.

Rhododendron ‘Double Winner’. Photograph by Bill Heller

Rhododendron ‘Double Winner’. Photograph by Bill Heller

Red for Drama

For visual intensity, red undoubtedly adds the most drama to the landscape. Three in the red collection that bloom in late April are Rhododendron ‘Double Winner’, ‘Taurus’, and ‘Grace Seabrook’, the latter usually the earliest of these to bloom. Along with bright blood red flowers, R. ‘Grace Seabrook’ received handsome foliage from its parents, R. ‘The Hon. Jean Marie de Montague’ (a 2003 GPP) and R. strigillosum. The same parentage also produced R. ‘Taurus’ with its distinctive deep red buds in winter and glowing red flowers with black speckles. The only minor caveat is that ‘Taurus’ must be about five years old before it begins to flower, but it is definitely worth the wait.

Exceptional midseason and later flowering red selections include Rhododendron ‘Fred Peste’, ‘Markeeta’s Prize’, ‘Skookum’, and the sibling hybrids ‘Vulcan’ and ‘Vulcan’s Flame’. Each has its own worthy attributes along with diverse shades of red, including cardinal red, scarlet, and fire-engine red.

Rhododendron ‘Anah Kruschke’. Photograph by Al Dodson

Rhododendron ‘Anah Kruschke’. Photograph by Al Dodson

Purple Passion

Purple is such a popular color that Meerkerk Rhododendron Gardens on Whidbey Island, Washington has a special “Purple Passion Rhododendron Sale” in May (see What’s Happening, page 9). To quench a gardener’s thirst for this royal color, the Advisory Group recommends Rhododendron ‘Anah Kruschke’ (reddish purple), ‘Azurro’ (bright purple), ‘Edith Bosley’ (deep purple), or ‘Peter Alan’ (rich orchid with reddish shading), all with a darker eye. There is also R. ‘Blue Boy’ which, as the name suggests, has more blue in the flowers, bestowing a vibrant violet color with an almost black blotch.

Rhododendron ‘Naselle’. Photograph courtesy of Briggs Nursery

Rhododendron ‘Naselle’. Photograph courtesy of Briggs Nursery

Bicolors 

Bicolor rhododendrons have a contrasting color along the edge of each petal—either a thin, distinct margin of color called “picotee,” or a gradual shading to a darker hue. This two-tone coloration adds excitement and splash to the garden. Bicolored flowers can be used to blend one color scheme into another, but plan carefully. Choose one of the two colors on which to build your color scheme, as these bicolored flowers are best used as accents.

Of the selected bicolors, Rhododendron ‘Naselle’ has a unique shading of watermelon on the lobes, merging into light custard, with burnt sugar speckles inside the large, fluted blossoms. R. ‘Elsie Watson’ and ‘Hachmann’s Charmant’ have somewhat similar coloring, with a picotee edge of red purple and a white center; the former has a small maroon star in the center, whereas the latter has a large maroon blotch. The prolific flowers of R. ‘Fantastica’ are deep rose shading inward to a white throat. Daintiest of the group is R. ‘Manda Sue’, with shell pink petals that are scalloped and edged with red.

From southern British Columbia to Eugene, Oregon, and west of the Cascade Mountains, rhododendrons typify this horticultural region. While some may complain of an overuse of this beautiful shrub, there is no avoiding the fact that rhododendrons continue to be popular and well loved. In the Pacific Northwest, as the spring season is warmed by the sun, rhododendron flowers burst forth in shades of soft pink, clear yellow, brilliant red, and deep violet—rainbow colors that saturate the landscape and dazzle the eye. How can anyone resist?


2005 Great Plant Picks: Rhododendrons

Pink Hybrid Rhododendron Collection

‘Christmas Cheer’
‘Dreamland’
‘Janet Blair’
‘Mardi Gras’
‘Mrs Furnivall’
‘Noble Mountain’
‘Queen Alice’
‘Rosa Mundi’
‘Trail Blazer’
‘Very Berry’

Yellow Hybrid Rhododendron Collection

‘Capistrano’
‘Horizon Monarch’
‘Lemon Dream’
‘Nancy Evans’
‘Odee Wright’

Red Hybrid Rhododendron Collection

‘Double Winner’
‘Fred Peste’
‘Grace Seabrook’
‘Markeeta’s Prize’
‘Skookum’
‘Taurus’
‘Vulcan’
‘Vulcan’s Flame’

Purple Hybrid Rhododendron Collection

‘Anah Kruschke’
‘Azurro’
‘Blue Boy’
‘Edith Bosley’
‘Peter Alan’

Bicolor Hybrid Rhododendron Collection

‘Elsie Watson’
‘Fantastica’
‘Hachmann’s Charmant’
‘Manda Sue’
‘Naselle’

All selections in the Great Plant Picks have been chosen for their suitability in USDA hardiness zones 7 and 8, which covers most of the Pacific Northwest, west of the Cascades. Most rhododendrons will perform well in Sunset zones 4 to 6 and 15 to 17, although plants may not perform equally well in all of these zones.

To learn more about Great Plant Picks, please visit our website at www.greatplantpicks.org. There you will find photographs, fact sheets, selection criteria, and current evaluation reports. To join our mailing list, please call 206/362-8612.