gardening as a passion took me in its hold, one particular
group of plants began to capture my imagination, the cool
climate evergreen rhododendrons. Living at the time in
southern Tasmania, I was naturally drawn to the big, colourful
trusses of the popular hybrids. Each spring I spent many
an hour at the botanical gardens in Hobart watching and
waiting as one by one these splendid plants unveiled their
delights for a few short weeks before rain would come
to wilt their petals.
I realised there was much more to the vast and diverse Rhododendron
genus than the showstopping garden shrubs found in every
corner nursery. There are tiny, ground-hugging prostrate
plants, with spiky leaves and trusses of flowers no larger
than a five cent piece, that have adapted to surviving heavy
frosts and winter snows of windswept rocky outcrops in the
Himalayas. There are forests of trees with gigantic, leathery
leaves as much as a metre in length. And there are epiphytes
perching precariously in the forks of trees in the misty,
mountain jungles of southeast Asia and New Guinea.
rich variety of rhododendron foliage can equal the delights
of their blooms, especially the young spring shoots which
rise optimistically like candlesticks once the flowers are
spent. And an added bonus that is often overlooked in a
number of species and hybrids is fragrance to rival the
sweetest rose or magnolia.
in flowers is just one of several devices evolved by plants
to attract birds or insects as pollinators and a number
of species have survived by perfecting this trait. Fragrance
in the rhododendron is genetically linked to pale flower
colours, so that fragrance becomes an unfortunate trade-off
with colour. Any strongly coloured rhododendron can be guaranteed
not be fragrant.
About the only relief from white in fragrant rhododendrons
one can hope for are pale creams or lighter shades of yellow,
or perhaps a pink or purplish flush to the flower buds which
inevitably fades to white as the flowers open.
nuttallii, from the Himalayas, is a tough, generous
plant whose strongly scented, bold white flowers positively
glow from a vibrant yellow throat. It thrives in quite open
positions, and its large leaves are like sumptuous, deeply
grained green leather. R. lindleyi, also from the
Himalays, has a more open habit and less interesting foliage,
but crosses between the two have resulted in some very beautiful,
highly fragrant plants.
heat tolerance and suberb fragrance of R. maddenii
make it a good choice for Australian gardens. It is widely
variable in form and found across a broad area of southeast
Asia and the Himalayas. There are some pale yellow forms
of R. johnstoneanum from northern India, but as always
the rule is that the deeper the shade the weaker the fragrance
cream flowered R. dalhousiae is another evergreen
species that is closely related to R. maddenii and
worth seeking for its powerful fragrance. Its variety 'Rhabdotum'
offers the bonus of a bold red stripe along the side of
Fragrance is generally passed on to the hybrids of species
rhododendrons, and perhaps the best known of the fragrant
hybrids is the aptly named R. 'Fragrantissimum'.
Its Latin name suggests that it is a species but it comes
from the early days of hybridizing, when Latin names were
still permitted for hybrids.
is one of the edgeworthii hybrids, a cross between
the richly fragrant R. edgeworthii and the non-fragrant
R. formosum, both white flowering species from the
Himalayas. But one wonders why the uninspiring 'Fragrantissimum'
lanky and fairly sparse of leaf remains so popular,
when even the parent R. edgeworthii develops a far
superior garden habit. Its straggly, open form does, however,
lend the plant to training as an espaliere against a wall
sweetly fragrant plants with R. edgeworthii in their
parentage include 'Princess Alice' and 'Countess of Sefton'.
The more compact 'Suave' and slightly larger 'Daviesii'
have very similar, large simple white flowers tinged with
pink, and a fragrance to rival that of 'Fragrantissimum',
but they are far better behaved, compact shrubs.
Loderi hybrids were bred by Sir Edmund Loder around the
early 1900s, and are crosses which include two white flowering
fragrant species in their parentage, the Himalayan R.
griffithianum and R. fortunei from eastern China.
Probably the best known of these hardy, vigorous plants
are 'Loderi King George', with its enormous trusses of white
funnel-shaped flowers, and the more sun-tolerant and compact
island of New Guinea is the domain of the vireya rhododendron
and is home to over two hundred species with certainly more
treasures awaiting discovery. Others are found scattered
across much of southeast Asia, with two very similar red-flowering
species, R. lochiae and R. notiale, native
to the far northeast of Queensland.
years have seen the release of many new vireya hybrids with
forms superior to the often leggy species, as these versatile
plants rapidly gain popularity. So long as sufficient sunlight
and some protection from frost can be provided, vireyas
may be grown in gardens as far south as Hobart.
of the vireya rhododendrons are strongly scented, probably
the best known examples being R. konori from New
Guinea and R. jasminiflorum from Malaysia, Sumatra
and the Philippines. The unique R. tuba, also from
New Guinea, is an unforgettable sight in flower, massed
with trusses of dangling white tubular flowers with a heady
of the evergreen azaleas offer fragrance, although there
are a few notable exceptions. 'Alba Magnifica', also known
as 'Alba Magna', is an enduring, vigorous Indica hybrid
from the 1850s, whose tolerance to sunlight makes it an
ideal choice for planting in massed beds in an open setting,
concentrating its subtle scent.
rare exception to the pale colour rule is the mildly perfumed,
pale mauve hybrid 'Schryderii Mauve', a sport of the equally
fragrant white 'Schryderii'. Both plants have sticky foliage
which potentially harmful insects avoid.
Many deciduous azaleas can be delightfully fragrant. R.
occidentale, the western azalea, grows wild in temperate
zones west of the Rocky Mountains. It is a particularly
captivating plant whose white flowers bear a distinctive
golden yellow flare, a characteristic passed on to other
occidentale hybrids, such as 'Exquisita' and 'Delicatissima'.
massed flowers of many deciduous azaleas burst open dramatically
on bare branches before the foliage emerges, providing a
striking contrast in an otherwise often bleak early spring
landscape. The eastern European species R. luteum,
which has a very strong fragrance resembling honeysuckle,
is one such plant. A parent of many hybrids, its yellow
flowers are among the strongest in colour of the scented
rhododendrons, and it is also noted for its dramatic autumn
not just the flowers of the rhododendron plant that can
be fragrant. A characteristic of the red to yellow flowering
R. cinnabarinum, from the Himalayas, and one
that is passed on to its many offspring, is the cinnamon-like
aroma of its bluish green foliage when rubbed against or
plants with aromatic foliage include the species R. campylogynum,
whose sulphur yellow flowers are also slightly fragrant,
the pink or white R. glaucophyllum and and the purplish
blue R. hippophaeoides, all Himalayan plants.
There are several forms of the heat-tolerant American hybrid
'P.J.M' in various shades of pink, and all with aromatic
foliage. All of these plants demand siting alongside paths,
where they will be brushed against, adding yet another dimension
to the garden sensation.
final word of caution. The flower parts of the rhododendron
and even the honey from bees which have visited the plants
can be highly toxic.
the Western Highlands of New Guinea the flowers of the vireya
R. macgregoriae are used in the preparation of baits
for rats. Around 400 BC, a Greek army was stopped in its
tracks after consuming the sweetly flavoured honey from
bees that had visited the flowers of R. luteum. The
poison is a narcotic which has been known to cause respiratory
failure, so certainly sniff and enjoy the fragrance, but
avoid touching or handling the flowers of any rhododendron.
with all rhododendron types depends very much on providing
the right soil conditions before planting and correct siting
for each particular plant. Like other members of the erica
family to which it belongs, rhododendrons enjoy a cool root
run in constantly moist but freely draining and acidic soil,
ideally with a pH level between 4.5 and 5.5.
will bitterly resent a poorly draining soil which can often
be overcome by mound planting in more friable soil raised
above the surrounding ground level. Moisture levels can
be maintained and soil temperatures moderated by maintaining
a deep mulch of organic material and the use of drip irrigation
in low rainfall areas.
but certainly not all, varieties prefer protection from
strong winds and some level of light or dappled shade, particularly
from the afternoon sun in summer, although many varieties
that are sun tolerant are now clearly labelled as such by
pruning is normally necessary, although 'dead-heading',
or removing the spent flowers on younger plants will encourage
pests and diseases pose a serious threat to rhododendrons.
Most problems that do arise result from poor growing conditions,
such as lack of ventilation and insufficient or excessive
rhododendrons with an application of slow-release fertiliser
pellets at the standard rate or a combination of organic
materials such as blood and bone and well decayed compost
in late winter or early spring. The root systems of rhododendrons
grow very close to the soil surface and into the mulch,
so avoid any cultivating around established plants.
'Countess of Haddington'
'Countess of Sefton'
'Mrs. A. T. de la Mare'
'Van Nes Sensation'
'Mother of Pearl'
'Sir Frederick Moore'
'Bob's Crowning Glory'
'Dr. Hermann Sleumer'
'Esprit de Joie'
'Highland White Jade'
deciduous azalea species
deciduous azalea hybrids
evergreen azalea hybrids
specialist rhododendron suppliers in Australia
Grove Nursery, Cattai
Ridge Road, Glenorie, NSW 2157. (02) 9652 1200.
Rare Plants, 686 Mount Macedon Road, Mount Macedon,
Vic. 3441. (03) 5426 3075.
National Rhododendron Gardens, The Georgian Road,
Olinda, Vic. 3788. (03) 9751 1980.
Valley Nursery, Woori-Yallock Road RSD, Cockatoo,
Vic. 3781. (03) 5968 8676.