ABOUT RHODODENDRONS

Otago Daily Times, Issue 21940, 29 April 1933, Page 2

ABOUT RHODODENDRONS

Rhododendron culture, which has made such enormous headway during the last decade or so, has had as much influence upon our rock gardens as it has upon woodland and glade (writes A. T. J., in the Amateur Gardener). The hosts of species and forms recently sent home by collectors have included a large number of little moorland and alpine shrubs, which have proved ideal subjects for the rock garden. These plants, most of them evergreen, are mainly quite hardy, and as easy to grow as heaths in any lime-free soil that is well drained. They may be given some leaf mould at planting time and granulated moss peat is always useful, both in the soil and as a mulch to retain moisture. But they are not fastidious and can be relied upon to flower well and carry on indefinitely under average rock garden conditions, either with full sun or light shade. Propagation is by no means difficult by cuttings, and many kinds can be raised easily and quickly from seed.

In the past alpine rhododendrons have been scarce and expensive. But if there are still many rarities among them, there is also a considerable number now within the means of most, and every season increases the selection, and brings the gems of this great family nearer the average amateur. The list here given is confined to those now readily obtainable from nurseries catering for such plants.

FOR THE ROCK GARDEN. No group is more worthy of first mention than the lapponicum. Two of the prettiest, of this series are R. fastigiatuni and R. impeditum, low and compact twiggy bushes, with flowers that vary from lavender blue to violet, the former having a silvery foliage, while that of the latter is dark green. R. intricatum is a delightful shrub, with grey green foliage, and flowers of a soft lavender. R. scintillans is another very charming species, with blooms of a gentle harebell blue and narrow golden green leaves. Then there is the striking rv.ssatum, with red brown foliage auj deep blue purple flowers, and It. hippophaeoidcs. The latter is the tallest of the clan, but it may he kept down to 18 inches by careful pruning and full exposure. This is a lovely shrub, its blossoms ranging from pale lavender to violet. In common with the rest of its class, it will often supplement its spring flowers by an autumnal crop. These lapponicums happily give us some yellowflowered species, which are invaluable for associating with the blue shades. Among the best of these are R. flavidum {primulinum), R. chrysoum, and R. muliense. R. racemosum is in every way a firstrate rock plant, differing from most of the genus by bearing its flower clusters at the leaf axils as well as at the tips. The petals are a fresh rose and white, the young wood is red, and the leaves have a glaucous sheen. Forrest and Wilson introduced some low-growing It. racemosums with flowers of a beautiful bright rose and a low-spreading habit, and these are now obtainable. All this group, including R, oleifolium, can be

strongly recommended for ledges that will accommodate shrubs of from two to four feet.

R. glaucum, a squat, spreading species, with large, bell-shaped, rosy blossoms, is another good rock shrub, but it does be,st with light shade. The magnificent R. VVilliamsianum has a very similar habit, and is one of the choicest of all dwarfs. The foliage is charming, and the enormous campanulate flowers arc a full deep rose. R. calostrotum and R. riparium must also be included here, for they are not difficult to get or to grow. Their lovely foliage, hoary with silver or rusty gold, and deliciously aromatic, makes a perfect setting for the big crimson purple bells.

R. ciliatum is an early bloomer, and grows to several feet, but. its large rosy white blooms are borne on quite small plants, and growth is very slow. Another early one is the delightful R. prmcox, a hybrid from the last-mentioned, with exquisite flowers in a cheerful rosy lilac. Where this is liable to . get marred' by .spring frosts the rather later R. cmasculum makes an admirable substitute. ,R. ferrugineum, the “ alpine rose,” and R. hirsutum are useful for the bolder parts of the rock garden, and with them one may include the more showy R. Wilsoniaum, R. arbutifoliura and R. tendlum,

For a moister • spot than any of the above require that choice shrublet of two feet, R. ledoides, with fragrant foliage and rosy white, daphne-like clusters of sweet-scented flowers, must not be overlooked. Its ally, the very similar R. sphmranthum, is almost as charming, ami the alpine plant enthusiast should also have the dainty R. canadense (Rhodora). When planting these choice gems bear in mind the necessity for thorough drainage. See that the. soil mixture is loose and friable—not liable to cake in dry weather—and instead of ramming it firmly down; merely press it very gently about the roots, Avoid deep planting. Every rhododendron should be set with its upper roots only just covered, and that with some loose, leafy or peaty material. After spring planting an occasional soaking with rain water will be necessary.