By Roy L. Hudson
Supervisor of Maintenance, Golden Gate Park
San Francisco, Calif.
It is becoming increasingly evident that all species and hybrids of rhododendron cannot be grown to perfection in any one locality. Even where considerable care is given to provide good growing conditions, such as preparation of the soil, protection from wind and ample artificial watering, some varieties will sulk and refuse to grow and bloom satisfactorily. This is by no means surprising to those who have a superficial knowledge of the tremendous range from which the various species have been collected. Indeed we are frequently surprised to find how tractable some species can be under cultivation at great variance with its natural habitat. If we are fortunate we sometimes find a species or a hybrid that is so happy under our own particular conditions that it outdoes itself and forces our interest and attention upon it. Such a rhododendron is the subject of these notes.
Rhododendron burmanicum of the series Maddenii, sub-series Ciliicalyx, is listed in the Year Book of the Rhododendron Association as a two star, "pretty shrub 6 feet or more in height, with greenish-yellow or greenish-white flowers, sweet scented." It also bears the fatal F mark of the tender or greenhouse variety. Surely the above description would never cause a burning desire to possess this species.
For some years a single specimen has been growing in the Strybing Arboretum in Golden Gate Park without attracting much attention. It was lost in a heavy planting of large flowering hybrids and was leggy in its search for light. It did bloom however and set some fat seed pods which were collected by one of our nursery staff some five or six years ago. The seed germinated strongly and rapidly and a hundred or more seedlings were planted in flats where they developed with extreme vigor. Because they were so lightly regarded and because the lath houses were full they were planted out in a nursery row of what had been a war time vegetable garden with very slight preparation and very ordinary care. Most of them were in full sun and wind although the row ran under trees at one end and was quite shady. The soil was light and sandy with very sharp drainage but the area was well watered. Our attention was soon attracted by the lush deep green foliage and rapid growth and the entire lack of sun-burn or wind-burn. To our amazement they began to bloom the third spring while only two and a half years from the sowing of the seed. These first trusses were borne at the terminal of the main leader and seemed huge on the compact young plants. The color was not "greenish-white" but a cool greenish-gold which slowly aged to a rich cream. The habit of the plants and the size and color of the flowers were strikingly uniform and no variation was discernible at this time.
When planting in the John McLaren Memorial Rhododendron Dell got under way these plants were transferred from the nursery row into a fully exposed bed. They were planted in a mixture of sand, tule peat and pine needles no better and no worse than is provided for the rest of our species and varieties. They moved easily, settled down immediately and not a single plant was lost. In November a few flowers appeared and from then on until June it was always possible to find a few trusses. No other rhododendron, species or hybrid, has had as long a season.
In late April and May the big show comes when the entire plant becomes a mass of gold and cream with a hint of green in the unopened buds, truly a magnificent sight. Every tip on the plant bears a truss of flowers every year whether the spent blooms are removed or not. If left on they set heavy crops of seed which ripen quite late in the year. The flowers are excellent for cutting and may be used freely as the plant has a self-branching, stump-sprouting habit. The new growth fills in rapidly and blooms as freely the following year as the uncut plants. The plant is compact and leafy and well furnished from the ground up. The leaves are of medium size and in perfect scale with the flowers which are boldly borne and not hidden by foliage. It is attractive the year around and never has the ugly off-season look of the triflorums and many other species.
Truly a great rhododendron for us. The fault that prevents it from becoming a widely planted species is its lack of hardiness, but even that is subject to some revision. Our plants have gone through some heavy frosts, fully exposed and without protection of any kind. I have never discovered a burned tip or a blasted bud in our five or six years experience. Of course we grow R. 'Fragrantissimum"; 'Countess of Sefton'; 'Countess of Haddington' and other so-called "Himalayan hybrids" all over the place without winter loss.
It is interesting to note that as the slants grew older a few minor differences began to appear in the flowers. One seemed slightly larger in the individual corolla and one is definitely a deeper yellow than all the rest. Needless to say it will be the one that will be propagated by cuttings, which, by the way, shrike readily. I am positive that this one species will go a long way toward taking Rhododendrons out of the specialist class and making them garden shrubs for everyone's garden, at least in the Bay Area.
It has been my pleasure to attend every meeting of the California Branch of the American Rhododendron Society during the past year and I have taken this species to many meetings to prove its long blooming habit. Considerable interest was aroused and seed which was passed around is being grown by many of the members. Those who hybridize are particularly interested in it and some interesting crosses are being planned. It would be well to keep Rhododendron burmanicum in mind. Its future is assured.