Satsuki Evergreen Azaleas Extend the Blooming Season of the Genus Rhododendron
By Corinne Kennedy
‘Shinnyo-no-Hikari’ Satsuki azalea (Rhododendron ‘Shinnyo-no-Hikari’), planted next to the Seattle Japanese Garden’s dry stream bed, Area C. (photo: Kathleen Smith)
Broadleaf evergreens—and particularly evergreen azaleas—are arguably the most important plant type in Japanese-style gardens. Originally in a genus of their own, azaleas were reclassified in the 19th century. Now they’re included in the genus Rhododendron along with “true” rhododendrons. “Azalea” is simply a common name.
Azaleas are widely planted in traditional Japanese gardens, including the Seattle Japanese Garden. Evergreen azaleas, in particular, tend to be more delicate in habit and flowers than “true” rhododendrons, and are easily shaped into low mounds. (Because most Japanese broadleaf evergreens weren’t available in 1960, our Garden’s Japanese designers agreed that “true” rhododendrons, readily available and popular in our region, could also be planted in the Garden.)
Though the azalea blooming season begins later than that of “true” rhododendrons, it extends from March into June when late-flowering kinds, such as the evergreen Satsuki hybrids, are planted. With their large, showy flowers, low-growing habit, and attractive foliage, they’re an elegant highlight of late spring and early summer—and my favorite type of evergreen azalea! At least ten Satsuki cultivars remain of those planted in the Garden’s early years, most located prominently along its main paths. (Several other June-blooming evergreen azaleas, with similar flowers and foliage, may be Satsuki hybrids, but records identify them only as “Rhododendron hybrids.” Other azaleas, such as Rhododendron ‘J. T. Lovett’ resemble the Satsuki, but may be Rhododendron indicum species rather than Satsuki hybrids.)
SATSUKI CULTIVARS IN THE SEATTLE JAPANESE GARDEN:
Area B (Inside the south entry gate, west of the path):
‘Myogi’—white, ruffled flowers with a few tiny flakes of purplish-pink; planted in 1964. (photo: Aleks Monk)
‘Gumpo White’—ruffled white flowers have overlapping petals, light green centers, and occasional small flakes of purplish pink.
Area C (Inside the south entry gate, east of the path):
‘Chukyo-no-Haru’—flowers are light salmon-pink, with darker markings; planted in1962. (photo: Kathleen Smith)
‘Ro Getsu’ [“Wax Moon”]—flowers are white or deep pink, most with pink flecks, stripes, sectors or centers; may have been planted in 1967. (photo: Kathleen Smith)
‘Shinnyo-no-Hikari’ [“Eternal Light”]—flowers have wide, overlapping petals, and are pale pink or white, with darker rose-pink flakes, stripes, margins & sectors; planted in 1962. (photo: Kathleen Smith)
Area H (Along the east side of the pond, south of the bridges):
‘Jindai’ [“Divine Age;” also planted in Areas E & X]—flowers are white or pale pink, with darker pink flakes, dots, sectors or stripes; some flowers are all white, pink or dark pink; planted in 1964. (photo: Kathleen Smith)
‘Gunrei’ [“Beautiful Group”]—frilled flowers, with wide overlapping petals, are white or pale pink, with light pink flakes and small sectors; planted in 1962. (photo: Aleks Monk)
Area P (At the north end of the pond. This cultivar is planted there underneath the Yamasaki black pine. Also planted in Area O, at the foot of the steps to the Kobe Lantern.)
‘Gosho Zakura’ [“Cherry of Imperial Palace”]—ruffled flowers are white or pale pink, with occasional darker pink markings; planted in 1974. (photo: Kathleen Smith)
Area X (A small area, surrounded by paths, south of the teahouse garden):
‘Bunkwa’—flowers are light pink with greenish throats; planted in 1962. (photo: Kathleen Smith)
Area ZZW (Along the west-side fence in the southern half of the Garden. This cultivar is planted in the southernmost part of Area ZZW.)
‘Tochi-no-Hikari’—relatively small flowers are white or pale pink with blotches consisting of darker dots; planted in 1962. (photo: Kathleen Smith)
IN JAPAN, AZALEAS HAVE BEEN CLASSIFIED INTO TWO TYPES:
“Japanese gardeners distinguish between two kinds of azaleas - the Tsutsuji and the Satsuki. The Tsutsuji bloom about 30 days after the spring equinox with flowers produced before new growth begins. The Satsuki azalea, whose name translates to “fifth month,” blooms 60 days after the spring equinox. More than 500 cultivars of Satsuki azaleas have been described, with almost all having unfamiliar-sounding Japanese names.” (Gerald Klingemann, University of Arkansas Extension Horticulturist)
SATSUKI EVERGREEN AZALEAS—ORIGIN AND DESCRIPTION:
Satsuki azaleas likely originated in Japan as natural hybrids between Rhododendron indicum and Rhododendron eriocarpum (also known as R. tamurae), species that occur on Japan’s southern islands. Hybridized there for at least 500 years, they’re beloved for their elegance and beauty.
These evergreen azaleas are known for their large, showy, mostly single flowers, 1-5 inches wide, that open in late May and June. Some plants, however, have hose-in-hose, semi-double or fully double flowers. Flower shapes include not only rounded, overlapping petals but also narrower, more widely spaced petals. Their edges vary from flat to frilled. Colors include white, pink, salmon-pink, red, reddish-orange, and purple.
Many of the wild-occuring hybrids displayed interesting color patterns—resulting in Japan’s long tradition of breeding for multiple patterns on the same plant (including solids, stripes, flakes, lines, sectors, and margins on lighter backgrounds). Not particularly stable, these patterns varied significantly from year to year—even on the same plant. After years of careful observation and breeding efforts, the Japanese developed a detailed system of classification—including more than twenty color pattern categories with evocative names—described in the 1692 book, A Brocade Pillow. [For example: Sokojiro (white throat); Tsumabeni (red fingernail); Hakeme shibori (brush variegation); Harusame shibori (spring rain variegation); and Fukiage shibori (fountain variegation).
When I stay at home to admire my azaleas, the bare room in which I live becomes, for a moment, a fairy castle. As I gaze at the blossoms, my head pillowed on my arm, I feel as if I am resting in a brocade bed, and so I have called this book A Brocade Pillow.
(Ito Ihei, mid-seventeenth century azalea authority)
The rounded to lance-shaped and often lustrous leaves of Satsuki azaleas range in length from about half an inch to two inches. A few cultivars have twisted foliage or variegated leaves, blotched or margined in yellow. Most are compact and slow growing plants, but some are faster-growing and more upright, reaching about 6 feet in 10-15 years. A few have weeping habits.
Most Satsuki azaleas are cold-hardy to USDA Zone 7 (minimum temperature 0 degrees Fahrenheit), but some are hardier, to USDA Zone 6. Like most azaleas, they perform best in moist, acidic, highly organic, well-drained soils, in morning sun and afternoon shade. They require regular watering during our region’s dry summers, but with regular irrigation will tolerate full sun, though flowering time may be reduced.
Satsuki have been planted for hundreds of years in the gardens of Japan. Though minimal pruning is required, they are generally pruned in Japanese-style gardens into traditional shapes. Tamamono is a low, mounded shape at least twice as wide as tall; o-karikomi is a wavelike shape of connected tamamono forms. Moreover, with their compact habits and small, fine-textured leaves, they’ve long been shaped into bonsai.
SATSUKI AZALEAS IN THE WEST AND IN THE SEATTLE JAPANESE GARDEN:
Satsuki azaleas came rather late to the West, including the U.S. After only a few had been introduced in the early 1900s, 53 named clones were introduced in 1938-39 by Ben Morrison, a well-known azalea breeder for the U.S. Plant Introduction Service; later, in the 1970s, an additional 387 cultivars were introduced by Barry Yinger of the National Arboretum. Breeders in the West have benefited, using them as parent material to develop their own creations.
We’re fortunate that so many Satsuki azalea cultivars remain in the Seattle Japanese Garden. Most are pruned in the tamamono or o-karikomi shapes, bringing mass and stability to the Garden and contributing to the simplicity and tranquility that visitors encounter here. I love their flowers, with their intricate and surprising color patterns—beautiful, interesting and playful—bringing joy and respite during these troubled times.
Corinne Kennedy is a Garden Guide, a frequent contributor to the Seattle Japanese Garden blog, and a retired garden designer.