Little Sweetheart Rhododendrons

Much as I love the big, bold, beautiful Rhododendrons, I have a small garden so I grow mostly small species and hybrids. Some of my all-time favourite species are R. pruniflorum, R. sargentianum and R. campylogynum. As container specimens, all have been reliably hardy for me in the Victoria area for many years and all are easy growers.

I started with small well-rooted cuttings, originally grown in 4 inch pots and over time, have moved the plants up to larger containers. The current pot size capacities are, more or less, 3 gallons. My potting mix is coarse peat, perlite, some coarse sand and if I've got it, a bit of garden compost. I do want a well-drained mix, so there's no more than about 40% peat in the mix. I know many people are cautious about fertilizing some Rhododendron species, but I give my container-grown plants a light application of slow release fertilizer in the early spring. Since they're in pots, there's considerable leaching so I think some fertilizer is appropriate. Some of our local growers just top dress their potted rhododendrons with Seasoil (a form of composted fish fertilizer) once each spring, and this works well for them.

I keep my plants in a location where they get full sun in the morning, but by about 1 pm, they are in the shade. Good light is needed to set flower buds, so if you have some of these smaller species and they're not blooming for you, perhaps a bit more light is in order. I water freely on an as needed basis, and I make sure the drainage holes remain open since there can be problems with containers if they're sitting directly on the soil surface where the holes may gradually get plugged. I like to have some sort of top-dressing on the soil surface to prevent too much surface compaction from all the watering I do. A good layer of orchid bark makes an attractive mulch, but sometimes I use turkey grit, or small-sized pea gravel. However, if you like to show your plants, most show judges prefer to see bark mulch used as a top-dressing as they often think write comments that they think gravel isn't aesthetically suitable for rhododendrons. Personally, I like the look of gravel or grit and it lasts longer than orchid bark.

Rhododendron pruniflorum has thimble-sized bell-shaped flowers of a dusty plum colour. It's absolutely adorable in bloom. The leaves are small, a nice dark green on top and white underneath. My 6-year old plant is about 18 inches tall and 18 inches wide. Many of us grow R. campylogynum and there are several forms available - all of them are very nice. But, my favourite (and I have a couple of forms) is R. campylogynum Leucanthum. Again, the thimble-sized flowers are bell-shaped, but in this case they are white in colour. Rhododendron sargentianum has small, ball-like trusses of white to ivory coloured tubular flowers. The tiny leaves are a nice shiny green and if crushed, give off a scent. The scent isn't unpleasant, but it makes me sneeze. I have a plant of the straight species, but recently acquired a plant of the selected variety 'Liz Ann' which is stunning in bloom as it just covers itself in pure white flowers. These plants are also about 18 x 18 inches and range in age from 3 to 7 years old.

A very similar looking plant to R. sargentianum is R. primuliflorum, but, with primuliflorum, the tubular flowers range in colour from white to soft pink and even yellow. It also has scented foliage. I've just recently been given a pink flowering form of R. primuliflorum and I'm looking forward to seeing it in bloom next spring.

One of the advantages of growing plants in pots is that I can move them onto the porch when the plants are in bloom, so while the plants and their flowers are small, I can get up close and personal with them easily. You know the adage, great things come in small packages, so if you only have a small garden, consider growing some of these lovely little sweethearts.

Rhododendron williamsianum

Rhododendron williamsianum, introduced to horticulturists of the western world in 1908 by Ernest "Chinese" Wilson is at once one of the most recognizable and one of the most enchanting rhododendrons. Its unique combination of almost orbicular, mid-green leaves, spreading and somewhat rounded or dome-shaped habit, and disproportionately large, candy-pink, campanulate flowers make it easy to recognize and well-adapted to gardens both large and small. Its densely mounded shape often has a somewhat brooding appearance, a bit like having a very large toadstool in the garden...but its solid presence makes a good anchor to a plant grouping, and can provide an effective screen, if needed.

Although never thought of as a large rhododendron, it can in time become quite massive, spreading up and out in large billowy curves that are certainly beyond the reach of vertically-challenged gardeners.

R. williamsianum flower
Photo by Chris Klapwijk

It was a species that has so captured the imagination of rhododendron fanciers that a veritable frenzy of hybridizing ensured. After all, there were so many positive characteristics to try to attach to other rhododendrons: small, tidy, glabrous leaves, with lovely bronze new growth, well-shaped, pretty pink blossoms that were large in relation to the leaf size, and a spreading compact habit that keep the blossom down where people could easily admire them.

Looking through Salley and Greer's book Rhododendron Hybrids, I gave up counting at the end of the C's, having reached something over 55 hybrids. Each decade seemed to bring on a new wave of williamsianum crosses:

  • Rothschild in the early 30s, including the iconic hybrid 'Bow Bells'.
  • Lord Aberconway in the late 30s and early 40s, with a whole series of hybrids beginning with "A" ('Adrastia', 'Adrean', 'Amata') as if he were trying to get in first in the Yellow Pages, but also developing the wonderful 'Cowslip', a williamsianum x wardii cross.
  • Hobbie in the mid 40s, with his 'Gartendirektor(s) 'Glocker' and 'Reiger'
  • all the way up to Weldon Delp and Hans Hachman's more recent hybrids.
  • Even J. C . Williams of Caerhays Castle used this namesake rhodo in his inspired 'Hummingbird' cross with R. haematodes.

R. williamsianum is truly endemic to Sichuan, China, being found only there, and even within that province its distribution is very limited. However, it is now in constant and widespread production and cultivation all over the world.

Fragrant Rhododendron fortunei

Plant hunter Robert Fortune discovered this lovely species in 1855. It is a fragrant rhododendron...but unlike those sweetly scented, tender beauties lindleyi, nuttallii and maddenii, R. fortunei is quite hardy.

Fortune's original collections were made in Chekiang Province, in eastern China, at about 3,000 feet. Other plant hunters later found the species in Anhwei, Kiangsi, and Hunan Provinces growing in woods and forests at 2,000-4,000 feet in elevation. Plant hunter Robert Wilson noted that the species was common on other Chekiang mountains, particularly in the Lu Shan range of the neighboring province of Kiangsi, to the west.

The leaves of R. fortunei are handsome, and show some variation. They are 3 to 7 inches long, 1.5 to 3 inches wide. A prominent and very attractive feature is the deep red of the midrib and petioles (leaf stems); these create a ring of color around the dormant bud that seems to deepen and become more conspicuous in winter. The leaves of the Lu Shan form are typically a dull, olive green in color, and have rich red petioles.

The flowers of R. fortunei are borne in a loose truss of 5 to 12, and are shaped like wide bells...funnel-campanulate. They are pink to pale pinkish-lilac or rose and are fragrant.

R. fortunei flower
Photo by Boris Bauer

R. fortunei has been much used for hybridizing, particularly in North America, and especially in the East...where it is appreciated for its tolerance of summer heat and winter cold. The two great hybridizers, Rothschild and Dexter, made free use of it this rhododendron as a parent. Indeed, one of the most loved hybrids of all time in eastern North America is Dexter's 'Scintillation'.

It is noteworthy that a particularly fine large flowered, sweet-scented R. fortunei clone was used as the seed parent of the original 'Loderi' hybrid grex. The other parent is R. griffithianum; a tender rhododendron found growing in the lower elevations of the Himalayas.

Adapted from Whidbey Island ARS Chapter newsletter, May 2003

"A" is for Rhododendron albrechtii

I keep a wish list of rhododendrons I want, and at the moment, the species R. albrechtii is included in the top three of my list.  I grew it in my old garden, but sadly, when I moved, it was one of the plants I had to leave behind.  I haven't found a replacement plant for sale yet, but I keep looking, and after all, the hunt is almost as much fun as growing the plant.  I may have to break down and order some seed of this species as it's not commonly available in the trade as established plants.

R. albrechtii
photo by Tijs Huisman

Why do I like it so much?  Well, in bloom it's such a sweetheart!  The plant I grew had deep cerise-pink flowers, two or three to a cluster, and each flower was almost 2 inches across in size.  In doing a bit of internet searching, I see other growers report floral colours ranging from the deep rosy pinks into the purple reds, and up to 5 flowers per cluster.  In the Pacific Northwest, R. albrechtii usually blooms in mid to late April.

The plant, native to Japan, is a deciduous azalea, and the leaves on my "old" plant turned a lovely yellow before they dropped in the fall.  I'm not sure if fall leaf colour is a constant for all albrechtii plants, but it's nice when it happens.  I had my plant situated on the north side of the house, but it got good light from mid-afternoon on into the evening.  It prefers areas with cooler summer temperatures, so avoid planting sites that receive hot temperatures and mid-day sun.  The usual recommendation of even soil moisture applies.  Plants grow to a height of about 4 feet, so R. albrechtii is a good choice for the small garden, or even a large container.  It's also a good choice for woodland plantings. Do keep an eye out for this great little plant – it should be on everyone's wish list.

 
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