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Species Rhododendron Descriptions By Name
R. sanctum

This deciduous azalea grows in the mountains of Japan.  The aniline rose to rosy purple flowers compliment the rhombic glossy leaves that are at first somewhat hairy.  It provides fall color to add interest to your garden and expresses all the restraint for which the Japanese garden masters are known. 

Here’s a plant to grow for its subtle grace.  The Japanese deciduous azaleas are underappreciated, often eclipsed by their flashier Exbury neighbors. It may reach four feet in ten years. It likes summer heat but not unrelenting sun.

R. sanguineum var. haemaleum

Here’s the darkest of the reds with flowers that approach black! Sounds strange until you see this plant in bloom, especially if it’s backlit by the sun. The flowers GLOW. Better still, it’s a dainty shrub, well rounded with leaves that have a silvery gray white underside, but it’s really good at drawing attention to itself.

This beauty wants a bright spot but insists its roots stay cool (that's temperature, not style). Hot sun is not its favorite - best grown in morning sun or on a north facing site. Give it small amounts of fertilizer on Valentine’s Day and Mother’s Day. Good drainage (perfect is better) is a must. This rhododendron may reach four feet in ten years. It blooms in May and is hardy to 0° Fahrenheit.


R. schlippenbachii

A deciduous azalea, R. schlippenbachii is a long-time favorite native to Korea and Manchuria. Its rounded leaves are held in distinctive whorls and finish the season in shades of yellow and orange in the fall. Flowers range from pink to white and appear before or with the leaves.

R. schlippenbachii makes a well-rounded shrub that may reach five feet in ten years. It prefers some shade, especially in the afternoon. Hardy to -10° F.  It is often known as the Royal Azalea.

sanguineum haemaleum
R. seinghkuense

Here’s a creepy, crawly wonder from Yunnan, Burma and Tibet that delights with foliage and bloom. Flat faced yellow flowers, singly or in pairs, add spice to bullate (puckered) foliage that that is tinged with rusty shades of orange and lots of hairs.


R. seinghkuense is an epiphyte, hence the basket (or container) presentation.  Besides, it should be protected from extreme cold, so mobility is a plus. R. seinghkuense is named for the valley in Upper Burma where it was first “discovered” by Kingdon Ward.  Its shoots are wooly and hairy too.

R. semibarbatum

R. semibarbatum is something of an oddity in the rhododendron world. First, it doesn’t look like a rhodo-dendron. It is the only member of its subsection, a Mumeazalea, and it looks more like a Menziesia than a rhody. (Menziesias have just been made rhododendrons!).


Grow this plant for its foliage – tinted light green with red shadings in the summer, then turning red, orange or yellow in the fall. R. semibarbatum comes from Japan, where it grows in the mountain forests. It is deciduous and stays fairly compact, with slender, spreading branches. It may reach four feet in ten years and is hardy to -5° F.

R. serotinum

Here’s a plant that has had a rough past.  Called “scraggly” from inferior garden specimens, the “real” R. serotinum was introduced in the late 1990s from China and North Vietnam, and it’s a plant with ATTITUDE.  White flowers appear in late summer and fill the garden with sweet FRAGRANCE.  The wavy margins and the bluish cast of the leaves make it the more interesting.  Truly a fine new introduction.

R. serotinum thinks it’s a tree, which it will become. Remember, trunks take up little garden space, so there’s always room to plant around and under (Rhodies play well with others).

R. sichotense

Imagine these flowers in January or February!  This plant will let you know that spring is right around the corner.  Coming from Siberia, it’s a hardy survivor that has some more surprises.  It will lose most of its leaves in the fall in a glorious show of yellow.  The leaves that remain will have a maroon cast all winter before returning to green in the spring.  And all the leaves are wonderfully aromatic.

R. sichotense grows into a willowy shrub, usually more upright than broad.  It may reach six feet in height in ten years.  It’s happy in a sunny exposure.  Like all rhodies, it appreciates good drainage.


Fertilize sparingly at Valentine’s Day and Mother’s Day.


This is a very useful species because of its hardiness and early bloom time.  It will take pruning so you can keep it to a size and shape of your liking.

R. sinofalconeri

This is a brand new species introduced to the west in 1995.  In its native habitat (SE Yunnan and N. Vietnam), R. sinofalconeri may grow in mixed forests, bamboo forests, or in its own magnificent rhododendron forest!


R. sinofalconeri wants to be a tree with big leaves and beautiful yellow flowers with a red blotch. As such, it takes up less than one square foot of your garden and ends the issue of whether you have room for another rhododendron   - of course you do. Think of what you can plant under it.

A mix of sun and shade is best. It may reach 7 feet in ten years, and it is hardy to approximately 5° F.

R. sinogrande

R. sinogrande sports the largest leaves of all the big-leaf rhododendrons.  In its native Yunnan, Tibet and Upper Burmese forests, it often grows near streams.  This plant wins every prize for sheer grandeur of leaves, which range from eight to thirty-six inches in length.


Flowers in big trusses are creamy-white or pale yellow with or without a blotch.  Our R. sinogrande plants have enjoyed living outside under stately fir, hemlock and cedar on the Olympic Peninsula since 1999 and have grown to fifteen feet in 25 years. 

R.sinogrande also makes a spectacular container plant.  We estimate it to be hardy to about 15° F, so it sometimes needs extra protection from the cold depending on how and when the cold develops. Overhead protection makes a big difference for this species. It enjoys being with other plant friends rather than being all by itself out in the open. It responds well to water and fertilizer.

R. souliei

The blue-green new growth and wonderfully soft light pink saucer-shaped flowers of this species make it a real princess of a plant.   Leaves are roundish and slightly heart-shaped and average about 2 ½” in length.  R. souliei is a nicely shaped plant and flowers freely even when young.  Well behaved, it won’t take over your garden. 

Its home is central and southwestern Sichuan, where it grows in forests of oak and spruce. It may reach four to five feet in ten years and is hardy to -5° Fahrenheit. It's tough to root from cuttings (impossible?) and is usually grown from seed.

R. spinuliferum

The forebears of these plants grow in thickets and pine forests in Yunnan and Sichuan. Its unique leaf and flower make it easily identifiable.  The flowers appear in clusters of upright, tubular, firecracker-like blooms in red, soft orange to white.  They are long lasting and always attract attention not to mention humming birds, who do all sorts of antics to get at the nectar. The leaves are long, pointed and have an interesting lighter texture with very prominent veins. It will enjoy some sun.

If you need your rhododendron to be a ball, this is not your plant. R. spiuliferum is a dancer, sending out new growth in all sorts of directions. Fortunately, it responds well to pruning. Therefore, height is up to you. We have espaliered one to the front of our greenhouse, others have used a fence. It's hardy to approximately 10° Fahrenheit.

R. stenopetalum var. linearifolium

Here’s another of those Japanese azaleas that are hard to classify. This plant has had a number of names since it was first described in 1870, but whatever it’s called, different should be right up there. Strap-like flowers and leaves are very distinctive. To keep this distinctiveness, it’s necessary to grow this character from cuttings. It likes some sun in moderation.

This azalea may reach three to five feet in ten years, but it responds well to pruning, so you can keep it “under control.”  It tends to be wider than tall and can provide a show in or out of bloom. It’s semi- evergreen and hardy to 0° F.

stenopetalum linearifolium
R. stewartianum

Here’s a plant whose flowers can be white, cream, yellow, pink, rose, or red!!  It comes from an area noted for its unique color combinations. The rounded leaves are unusual, and  the emerging leaf has a bluish cast. The plant will develop some peeling fawn-colored bark that adds interest.​

Found in bamboo thickets in Yunnan, Upper Myanmar (Burma), and SE Tibet, this plant is not often seen in western gardens.  Ours has grown to six feet in twenty years. The books say four feet in ten years. It is hardy to 5° Fahrenheit.


R. strigillosum

The clear, luminous red bell-shaped flowers of R. strigillosum are long and exceptionally brilliant. They appear very early in the season - first of March for us. The plant itself is another marvel. It's a rounded ball if grown with enough room around it, and its leaves are narrow, 3 – 7 inches long but not very broad, so that they look like bright green spikes.  The leaf petioles have stiff bristles as do the fresh stems, but those bristles are soft! New growth is spectacular.

Give this species a bright location - morning sun is fine but avoid cooking it in the hot afternoon sun. It will grow to 4 feet in ten years and is hardy to 0° F.

R. suoilenhense

Talk about big leaves! R. suoilenhense  is a new introduction from Viet Nam that sports incredibly large leaves on a plant that seems to display a remarkable amount of hardiness. As the plant gets older, the leaves will become slightly smaller and develop a tan indumentum which will fill in from the leaf edges at first and then continue to fill in more of the underside each successive year.

R. suoilenhense should bloom at an earlier age than most other big leaves with cream to white flowers with a red to purple blotch. Its exact hardiness is unknown – maybe 5° F? Height to be determined, but this is not a small plant.

R. sutchuenense

R. sutchuenense is an easy to grow, easy to bloom early spring thriller with flowers that are almost two inches each with up to twelve flowers per truss. It comes from Sichuan in western China where it grows in the woods amidst bamboo or evergreen oaks.  It tends to have an umbrella shape with age, so you can plant other garden goodies underneath.

R. sutchuenense will do best (and bloom more freely)  in a bright situation of some sun, some shade.  It also likes protection from strong or prevailing winds.  It tends to bloom at a young age and is hardy to -10° F. Five feet in ten years?

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