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G-H

Species Rhododendrons Descriptions By Name
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R. glanduliferum

R. glanduliferum is relatively new to us in the western world, first introduced from China in 1995.  It has proven worth the wait.  Large white flowers appear late in the season – July, August or September!  What’s more, they are deliciously fragrant.  The new growth follows and manages to harden up in time for winter.  It seems perfectly adapted to life in the Puget Sound area, growing to about six feet in ten years.

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R. glanduliferum has rather limited distribution in the wild and its habitat is under intense pressure from development. It makes a great addition to your garden.

glanduliferum
R. glaucophyllum

Here’s a bushy little fellow that will delight you with an abundance of flowers from a very early age.  The flowers come in shades of pinky purple, rose and pale pink.  The calyx, the outermost part of the flower in the back, is noticeably leafy, pointed and hairy!  Add to this that with age the bark peels away in shaggy strips, and R. glaucophyllum makes a wonderful addition for the smaller garden.

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R. glaucophyllum may reach four feet in ten years but probably won’t.  Its pointed leaves are quite aromatic and feature lots of scales on the underside (those little dots that are neither bugs nor disease).

 

It will like a somewhat exposed situation – the smaller leaves want more sun – but don’t bake it. Small amounts of fertilizer on Valentine’s Day and Mother’s Day, gentle watering – moist but not soggy and well-aerated soil with good drainage keep it growing well.

glaucophyllum
R. gongshanense

This newly introduced species grows in the Gaoligang Mountains of NW Yunnan, China, near the town of Gongshan. Light to dark red or pink flowers come in compact, attractive trusses. The foliage, rough and narrow, with prominent veins, is very distinctive. The new foliage’s striking bronze and yellow green colors just add to the pizzazz.

 

Because the flowers and new growth come very early – January or so – this plant is best suited for the milder areas. One of our seedlings growing in the garden has shown good hardiness, coming through some nasty winters unharmed  over its 20 years. We hope to provide cutting grown plants of this cultivar. It also seems to do well in a container.

gongshanense
grande
R. grande

R. grande is a stately rhododendron with an open, tree like structure.  Its narrow, long leaves are covered on the back with a plastered silver indumentum.  Early in the season, usually in February or March, R. grande blooms a lovely white with purple nectar pouches deep in the throat.

 

R. grande is native to the south side of the Himalayas – Nepal, Sikkim, Bhutan and on into northern India, where it may grow to 20 feet. R.grande makes a bold statement as a container plant – which is perfect because in cold under 15 - 20° F., you will want to protect it in a garage or greenhouse. In a container, it may reach 10 feet in 10 years. 

griffithianum
R. griffithianum

The flowers are the largest of any – up to six inches each and they are FRAGRANT!  R. griffithianum will develop a smooth, red trunk that rivals the flowers for attention.

 

It’s been hardy in West Seattle for the last decade, but if you are concerned about cold temps, feel free to protect it.  It will be fine in a container for several years.  It needs protection from cold below 15 - 20° F,, so if you can give your container some shelter (like your garage) during the coldest days, you will have a wonderful, spectacular rhododendron statement 11.5 months of the year! 

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R. griffithianum is the mother of the famous Loderi hybrids and deserves to be grown in its own right! The forebears of this plant come from the Himalayas (N.E. India).  In cultivation, it is expected to reach as much as 18 feet in 20 – 30 years.

habrotrichum
R. habrotrichum

Once again it’s foliage and flowers that give year-round pleasure. R. habrotrichum’s branchlets and petioles are covered in reddish-purple hairs that are bristly! Leaves are a dark green, slightly rugose on the top, glabrous on the underside, with glandular hairs on the edges. Flowers range in color from plum-rose to white-striped pink.

 

R. habrotrichum grows into a tidy mound, reaching four feet in ten years. It comes from the Yunnan-Burma border, growing in open situations. It must have good drainage and blooms at a surprisingly young age. It’s hardy to approximately 5° F.

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R. habrotrichum is a member of the Glishra subsection of rhododendron   classification. The series is noted for its hairy plants. Other members are R. crinigerum and R. recurvoides.

heliolepsis
R. heliolepis

It’s hard to know whether the best part of this plant is its flowers or its foliage. The flowers come later in the season – June or later, but the foliage always has an aromatic bite that manifests itself best on a warm afternoon but is available whenever you rub the foliage. The plant may reach five feet in ten years, and it responds well to pinching/pruning.

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Then there is the winter interest! Once things cool down, R. heliolepis responds with chocolate foliage in time for the winter festivities!

 

We recommend:

 More sun than shade, small amounts of fertilizer on Valentine’s Day & Mother’s Day, gentle watering with well-drained, well-aerated soil. It’s easy to grow, easy to bloom and performs when others are pooped out. (Those dots are scales).

R. henanense

It’s amazing how many “new” species are emerging from the Himalaya region. R. henanense was first described in 1983, and this is the first introduction in the West grown from wild collected seed. So far the plant branches readily and looks like it will make a nice mound. We expect it to reach 4 – 6 feet in ten years. We also expect white flowers with red or purple spots, but Mother Nature makes no guarantees. The stems of R. henanense are covered in soft hairs, and the leaves are outlined in soft hairs as well.  The picture above comes from Hans Eiberg of the Danish Rhododendron Society. His plant seems to match what we offer as R. henanense.

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We recommend more sun than shade but not the hot late day variety, small amounts of fertilizer on Valentine’s Day & Mother’s Day and well-drained, well-aerated soil. It doesn’t like wet feet. It seems to be quite hardy and hasn’t been fussy so far. Supposedly it has lots of flowers in the truss!

henanense
R. hodgsonii

The forebears of this slow-growing plant live in Nepal and Southern Tibet. Despite the large leaves, this species is very slow growing. When this plant blooms, the flowers will range from pink through purple-red.

 

This plant is popular for its rich, green leaves, and especially for the silvery new growth each spring.  The leaf underside exhibits a silvery indumentum.  With time, the plant develops smooth tan trunks. It is the most shade tolerant of the "big-leaved" rhodies.

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This species is named after the Englishman B. H. Hodgson, a former East India Company resident of Nepal. It may grow to five feet in 10 years and is hardy to 0°F.

hodgsonii
R. hookeri

R. hookeri has “hooks” on the back of the leaf.  You can feel them!  However, this is not why hookeri is named hookeri.  Coincidentally it was named for Sir Joseph Hooker, Director of Kew, botanist and traveler in the Himalayas. 

 

In any case, this plant has lovely red flowers that bloom in March/April.  The rest of the year this shrub provides a wonderfully smooth, red, polished trunk that adds to its interest.  We estimate it to grow to six feet in ten years and 50 feet in 100 years? It's hardy to roughly 5°F.

hookeri
R. huanum

R. huanum made its debut in the West in 1995.  It hails from Southwest China and graces itself with pale light purple flowers that are held loosely and gracefully.  The plant itself branches readily and makes a rounded shrub with narrow leaves.  So far it seems to be another winner among the plants missed (ignored?) by the early Western plant hunters.

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R. huanum is well behaved. It flowers readily at an early age and makes a fairly compact shrub that will not take over your garden: four to five feet height in ten years. It

wants some sun but doesn’t want to be cooked. (50% sun/shade might be just about right). Consistent gentle watering, good drainage and small amounts of fertilizer

on Valentine’s Day and Mother’s Day make it feel loved. It's hardy to 0°F.

huanum
R. hunnewellianum

This lovely plant can develop into a rounded shrub or small tree. Narrow, hanging leaves are pointed at both ends. It’s named in honor of H. H. Hunnewell, railroad baron and investor, who began importing and planting rhododendrons at his country home near Wellesley, MA, in the mid-1800s.  This led to their popularity in gardens and parks.

 

This rhody is native to the woods and thickets of Sichuan mountains (6,000 to 10,000 feet elevation). It is hardy to 0°F and may reach 5 feet in ten years.

hunnewellianum
hylaeum
R. hylaeum

R. hylaeum has two claims to fame, neither of which involves the flower. First, it has the most outstanding trunk – an absolutely smooth grey round that defies any attempts to climb it. Secondly, the new growth emerges a brilliant red-maroon.

 

We saw entire forests of 30 to 60 foot trees in Yunnan that had to be hundreds of years old. In our garden, 20 year-old plants grown from that seed have reached six feet. (Yes, you probably could climb ours, but please wait).

 

R. hylaeum makes a fine shrub for decades before it becomes a tree, and a great legacy to leave for your grand-children.  Give it a  bright location with partial shade from hot afternoon sun. Small amounts of fertilizer on Valentine’s Day and Mother’s Day will keep it happy as will gentle but consistent watering. Good drainage always helps. You can remove the lower branches to expose the trunk as it matures.

hyperythrum
R. hyperythrum

Here’s another winner from Taiwan (along with R. pachysanthum and R. pseudochrysanthum). This one comes from the north end of the island and is easily recognized by the recurved leaves (although the native plants seem to have flat leaves!). The leaves are somewhat stiff and are often held in a rigid manner. This plant means business.

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While most R. hyperythrum bloom white, there are pink-flowered forms as well. It has some heat tolerance and so may prove resiliant in a time of climate change. It may reach three feet in 10 years and is hardy to -10°F.

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