More Notes on Rhododendron Species at Royston
By Mary Greig, Ryston, Canada
What a wonderful winter we have had! Things that, in this cold garden, had perforce to be left out to the mercy of frost and snow, for lack of room in houses or frames, are as smiling and fat as if they had a home in a warm Washington or Oregon garden.
A great many of the rhododendron species which can be counted quite hardy in England or Washington, or even in Victoria hereon Vancouver Island, are only borderline with us. They may not be killed outright, but are nearly always damaged so much that it takes them all the following season to recover sufficiently to face another winter, when they areas likely to be killed as to survive. Rhododendrons griersonianum, leucaspis, megeratum, virgatum, crassum, lindleyi and many of the sanguineum and neriiflorum sub-series of the Neriiflorum series are among these. However, they are all small or moderate sized, and it is easy to do them well, and enjoy their flowering in bitter weather, in a cold greenhouse. With near zero temperatures, the houses must be heated, of course, to keep out most of the frost, but the glass alone makes about 10 degrees difference. This winter they needed no artificial heat at all. The Maddenii and Edgeworthii series do well in the same houses, and the touchier members of the Irroratum series. The two former series are nearly all very sweetly scented.
Many of the species, both from the hardiness standpoint and for decorative value, are at least as good as their hybrid progeny, and most of them have more individuality. On the other hand some are purely collectors' items, and have no garden value at all, other than interest. Some do need a long wait before flowering age is reached and others bloom well only every two or three years. However, many species flower long before they have reached maturity, and faithfully smother themselves with bloom year after year.
Fig. 18. R. moupinense An early blooming species that
has shown remarkable hardiness.
Most of the Triflorum series begin to flower before they are a foot high, and when in flower are as covered with blossom as the Beautybush. To keep them, or any other rhododendron, to the shape and size desired, all one need do is cut boughs for the house from the flowering plant, and very effective they are. At the moment (early March) a bowl of R. moupinense is quite enchanting, cut from a straggling bush badly flattened by snow two years ago. It has been in my rather warm room for more than a week, and is only now beginning to drop a few of its flowers.
Rhododendron euchaites flowers well every year, and begins at a very early age. No hybrid could produce a more vivid scarlet nor finer flower texture. However it could be hardier, 10 or 15 degrees of frost is as much as it can take without damage. The big sanguineum alliance is rather inclined to produce only a few flowers with us, but the best are very lovely. If rhododendrons, either species or hybrids are being grown from seed, it is important to be ruthless and destroy (not just give away) everything but the best. In some cases. even with true species, the best form may be a treasure and the worst completely worthless.
Almost all the Lapponicum series are consistent and prolific in flower, and they usually give a small display again in late summer. We have yet to see a hybrid which is better than the parents; though in a different way, they may be quite as good. And elsewhere, here too there is considerable variation in colour, but which is more desirable is largely a matter of individual taste. For some reason, we have found the two yellow species, chryseum (muliense) and primulinum (flavidum) much less easy to please than the purple and lavender species. The only white one we know, microleucum, is most lovely and not difficult.
R. trichostomum var. radinum is a shapely and elegant little bush, and it is always covered in season with masses of soft pink flowers, looking much more like a particularly delightful Daphne than a rhododendron. The tiny tubular flowers look as if they must be sweetly scented, but have no scent at all. Some of the anthopogon, if unscented in flower, do have very aromatic foliage, as do many of the Saluenense series. These latter are all open faced, nodding flowers, all dwarf, and all purple in varying degrees. We have not seen a good hybrid from them, but if their form and habit could be kept, with more variation in colour, they should be even more attractive and useful little plants.
In the Thomsonii series, R. souliei is free flowering, a delicate shell pink, and lovely in flower and leaf, and so is campylocarpum, which smothers itself with pale primrose trusses. These two are neat little bushes, in our garden not reaching more than 3 or 4 feet high and as much through, small enough to be planted in any garden. Campylocarpum var elatum is taller and more slender than the type, and a bright buttercup yellow, but so far, with us, not so generous in flower.
These few remarks do not, of course, cover anything like all the species which deserve to be grown for their own merit. None of the larger bushes and small trees have been mentioned even in passing, which is most unjust - however one must stop somewhere.
Our large plant of R. repens, of which I wrote several years ago (A.R.S. Bulletin, January 1950. Vol. 4, No. 1) looked very sick last spring, and alas by Fall was unmistakably dying. It is not completely gone yet, but I think is past all hope. Why? We have no idea-perhaps the two very cold winters, followed by an extraordinarily hot and dry summer were too much, but anyway a glorious career is finished. Some time ago we sold seed from this plant, and showed a lot of it ourselves, and the variation in the seedlings is amazing. Some are much more prostrate than others and leaves vary from half an inch to 1½ inches in length and from baths to an inch across. Some are still tiny and rather unenthusiastic-as one would expect, and others are running along the ground with a gusto that is most unlike its ordinary habit. What the cross, if it is one, may have been we do not know, but very few things are in flower as early as repens, and in our garden, none nearby. R. fulgens or R. euchaites seem most probable, but there is nothing in the seedlings, so far, to indicate either, or anything else. We shall have to wait and see, and maturity will he most interesting. We hope that seed customers will report on their plants if and when they flower. Of course, forms of repens are legion, and perhaps it is all natural variation, but if so, it is quite amazing.