Warren Berg's hybrid Rhododendrons

Some outstanding Rhododendron hybrids were developed by the late Warren Berg, who had a wonderful woodland garden in Pt. Ludlow, Washington. Warren was a plantsman extraordinaire and very much a part of the great Rhododendron hybridizing community in the Pacific Northwest.

Warren was one of the plant hunters who joined trips into Asia, particularly China, just as China re-opened to western plant hunters in the latter part of the 20th century. He often used seed of species he'd collected to grow plants and evaluate their potential both for local garden use and as parents in crosses. He wanted to create good, easy to grow small plants for modern gardens. He also wanted nice foliage displays as well as a range of flower colours.

Warren named his cultivars so people would recognize the hybridizer, and want to collect as many of his cultivars as possible. He often used "bee" in the hybrid name – the "bee" coming from his last name. So, you'll find plants named 'Patty Bee', 'Peter Bee', 'June Bee', 'Honey Bee', etc. There are exceptions, depending on who was being honoured with a cultivar name, hence the plant names 'Ernie Dee; and 'Ginnie Gee'. One of my favourite rhododendrons is 'Golfer', named for Warren's wife Patricia who was an avid golfer. 'Patty Bee' was also named for her.

R. 'Patty Bee'
R. 'Patty Bee'

One of Warren's favourite parents for hybridizing was R. keiskei 'Yaku Fairy', a dwarf, yellow-flowered species from the Japanese island of Yakushima. In addition to providing small plant stature, this species gave him genetic material for his yellow flowers as well as good foliage. And, it was a plant that would cross readily with other species to provide a range of flower colours.

R. 'Wee Bee'
R. 'Wee Bee'

For yellow flowers, look for 'Patty Bee', 'Peter Bee', and 'Golden Bee'. Good pink forms are 'Wee Bee' and 'Too Bee', and forms that are white, or open white flushed with pink include 'Ginnie Gee', 'Ernie Dee', 'June Bee' and 'Wanna Bee'. For one of the most outstanding foliage plants around, you can't beat the aforementioned 'Golfer'. This cultivar has lovely pink flowers, but what I really love is the new foliage that is so covered by indumentum that it appears white. By the end of summer, as the foliage matures, the indumentum is gradually lost, but is replaced with attractive blue-green leaves. They are all "good do-ers" both in the garden or in containers. So, "bee happy" and treat yourself to one of Warren's beautiful creations.

Cinnamon and Nutmeg

The use of cinnamon has been well documented since ancient Egyptian times, but it is actually native to southern China and the Island of Ceylon. Its value, even in ancient times, was such that it has been an important trading commodity from time immemorial. It continues to be one of the most important spices of the world.

Cinnamon is actually the dried inner bark harvested from two trees: Cinnamonum zeylanicum, native to Ceylon and southern India, or C. cassia, from southeast Asia. In the wild, the trees are about 40 to 50 feet tall, but for commercial purposes, trees are grown in plantations where they are severely pruned to be kept just over 6 feet tall. To harvest, twigs are cut from the trees, and the bark is carefully peeled off the twigs to form "quills". The quills are dried by wrapping them around another piece of wood, and during the drying process, the cinnamon ferments slightly. After drying, the quills are unwound and cut to short lengths for sale, or ground into cinnamon powder.

Cinnamon oil can be distilled from the bark, and this is used as a commercial flavoring agent and in the perfume industry. Usually, no reference is made as to which form of cinnamon is sold in a given package, but in North America, the "cassia" form of cinnamon is more commonly available, while Europeans and Mexicans prefer the Ceylonese form of cinnamon. Both forms provide a spice with a rich, aromatic scent and flavor, but the cassia form is thought to have a more robust flavor and the Ceylonese form is more delicate.

Cinnamon is commonly used in baking, in some processed candies and also is often added to pickles. Cassia buds, dried fruit capsules of C. cassia, are also harvested and dried for use in making pickles. The buds have a more pungent flavor of cinnamon.

Nutmeg is the seed of the nutmeg tree, Myristica fragrans. A related spice, mace, is also harvested from the nutmeg seed, but it is the leathery coating that is found wrapped around the actual "nut".

Nutmeg is a medium-sized tree, native to Indonesia. It is now grown throughout southeast Asia and in the West Indies. Nutmeg trees are dioecious, that is, male and female flowers are borne on separate trees. In planting a nutmeg orchard, the grower must ensure there are enough male trees to pollinate the female flowers so about one in every 10 to12 trees will be a male pollinator. Only the female trees bear nuts.

As they ripen, the nut's outer husk splits open, revealing a kernel, wrapped in the mace. After the nuts are gathered the outer husk is removed and the leathery mace is carefully removed by hand. The mace is pressed and dried. The remaining kernel consists of a hard outer shell with the seed inside. These nuts are slowly dried and when curing is complete the hard shell is removed. The kernel within the "nutmeg" is the actual spice and it can be packaged whole or ground. Both nutmeg and mace are used for flavoring sweet dishes, but they are also commonly used to spice meats, fish, preserves, and other food.

Indumentum and Tomentum

Many rhododendrons have felt-like coatings on the top or bottom of the leaves. Composed of small hairs, the coatings can be white, tan, reddish brown or dark brown colored. See photos for illustrative examples.

     R. proteoides      R. 'Sir Charles Lemon'

Indumentum (Latin, literally: "garment") is a coating of hairs on the undersides of a leaf. Tomentum is a coating of hairs on the top surface of leaves. Stems and flowers can also be hairy, and this is generally referred as “tomentose”. A plant surface with any kind of hair is said to be “pubescent”.

Indumentum forms a protective, woolly layer that sheds water and/or provides leaf protection. During cold, dry weather, the hairy indumentum that covers the leaf's underside becomes an insulating shield. Some of the plant hairs hold water and absorb it to provide the plant with moisture in times of drought. During times of heavy rain, the hairs are used by the plant to transpire excess water from the surface of the leaf. Indumentum also provides some protection from insect damage.

R. smirnowii      R. roxieanum

Indumentum types include: Hirsute (hairy, shaggy, long-haired), Pilose (long soft hairs), Villous (shaggy), Stellate (radiating in a star-shape), Scabrous (small projections rough to the touch), and Scurfy (very rough to the touch).

Cardiocrinum giganteum

This summer I've had lots of nice things in bloom, but the plant that made my summer was Cardiocrinum giganteum, as my plant finally bloomed after six years. It was lovely to see and worth the wait.

The first time I saw Cardiocrinum in bloom was in a New Zealand rhododendron garden where it was growing as a companion plant. Well, everything grows in New Zealand, so there were seedlings coming up everywhere as well as having plants in all stages of growth throughout the garden. I remember tip-toeing along a path trying to avoid stepping on plants when the garden's owner said not to worry, they were something of a weed for him. The next time I saw the plant was in its native habitat in the Himalayas. Again, just a spectacular thing and it stuck in my memory as one of those "wouldn't it be nice to try and grow". So, when I was given a one-year old seedling in the spring of 2014 I planted it immediately.

The site I chose gets morning sun, but is shady by early afternoon. Soil is on the heavy side and holds moisture fairly well, only requiring watering towards the end of summer when drought really takes hold. The first couple of years, I put some copper strips around the leaf perimeter to deter any slugs, but by year 3, the plant was strong enough to take care of itself.

Cardiocrinum giganteum


As you can tell from the species name, Cardiocrinum giganteum eventually gets big. The heart-shaped leaves are held on a central upright stem. The stem dies down in the fall and each spring, the new stem grows taller and holds more leaves than the year before. This year, the stem emerged, set out some leaves, as per usual, then it took off and grew vertically fast. There were times I imagined I could actually see it growing. At about 8ft, flower buds formed at the stem apex in June with flowering in July.

Flowers are white flushed with red in the center, trumpet-shaped and spectacular. My plant only had about a dozen flowers, but I've seen pictures where an individual flower stalk has up to 20 or so. Apparently, the bulb can set offsets, so I'll leave everything alone until next summer to see if I'm lucky enough to get some new plants. However, this is one of those plants that blooms once, sets seed and then the old bulb dies. So, I will try to collect some seed and once ripened, I'll try starting some new plants.

Cultivar definition

Cultivar is a hybrid word constructed from cultivate (from Latin cultus, to care for or cultivate) and variety (from Latin varietas, absence of monotony). A cultivar is a plant type that has been propagated to show specific characteristics reliably over time.

Crossbreeding or hybridizing is the most common method for creating cultivars. Hybridizing two plants results in a large variety of genetic recombinations, called a "grex" for short. More commonly, the results are called "sister seedlings".

Usually the hybridizer wants a consistent set of characteristics to be repeated over a long period of time. Seeds will not do very well, though some seeds, particularly for vegetable gardening, are called cultivars. For plants like Rhododendrons, we want to be sure each plant has the exact characteristics the hybridizer chose.

To get them, they can be propagated several ways. The easiest for the amateur is to grow cuttings. By taking shoots of a desired plant and raising them in a soil mixture until they are safely rooted, it is possible to get a fairly large number of plants that are alike.

A more difficult method that can produce huge numbers of identical offspring is meristem culture. In meristem culture, unspecialized cells from buds are shaken apart and grown separately to produce entire identical plants. This is definitely not a method for the amateur. but it used by many nurserymen to get hundreds of one specific cultivar at the same time.

Another way to get a desired cultivar is by grafting, although the method is seldom used anymore. The method gets good, healthy plants that bloom well, but there is a major drawback. Rhododendron ponticum from Central Europe previously was used as the stock plant for grafting rhododendrons. Eventually the stock plant has a tendency to produce shoots from below the graft, slowly out-competing the grafted plant. The same problem occurs with grafted roses and a number of other grafted plants.

There are some other ways to get a cultivar, including air layering or ground layering, but generally the easiest way for most of us to get a particular desired cultivar is to buy it from a nursery.

Rhododendron thomsonii portrait

Joseph Hooker found R. thomsonii in 1849 while exploring in Sikkim, India. Other plant collectors subsequently found this rhododendron species in Tibet, Burma, and Nepal.

R. thomsonii grows to be a small tree up to about 20 ft. tall in its native habitat, but it is unlikely to get more than half that size in cultivation. Typical height in ten years is about four to five feet.

R. thomsonii has attractive foliage. The leaves are two to four inches long, rounded or orbicular shaped. The new growth has a quite noticeable blue cast that becomes greener as it matures, eventually becoming dark green on the top of the leaf and lighter-colored on the underside.

On older plants, the reddish smooth bark begins to flake or peel and makes a beautiful contrast with the mixed brown, fawn, and pink new bark being exposed by the old peeling bark. This bark-flaking characteristic occurs not only on the trunk of the plant but occurs on the larger branches as well.

R. thomsonii is slow to flower. Flowers are 2-3" across, bell-shaped held in a loose truss of about 3-10 deep red flowers that have a contrasting large waxy cup-shaped calyx. This calyx can be whitish-green, yellowish-buff or greenish scarlet. The plant blooms in April.

R. thomsonii does best if planted in a location protected from the afternoon sun and late frosts.