Propagated by seeds; and cuttings of the growing wood
Rhododendron, Azalea (Rose-Bay). Ericaceæ.
Seeds are largely employed, but they are small and light and must be carefully handled. They are sown in spring in pans or boxes in a soil of sandy peat, care being taken to cover them very lightly and not to dislodge them when applying water. They are handled in cold-frames or in a cool house, and the young plants must be shaded. The plants are commonly allowed to remain a year in the boxes. Low growing plants are often layered. Cuttings of growing wood, cut to a heel, are sometimes employed, being made in summer and handled in a frame, but the percentage of rooted plants will often be small. Rhododendrons are extensively grafted, the veneer method being most used. The operation is performed upon potted plants in late summer or early fall, or sometimes in a cool house in early spring. Most of the leaves are allowed to remain upon the cion. The plants are then placed in densely shaded cool frames, and are nearly covered with sphagnum. Various stocks are employed, but for severe climates the hardy species like R. Catawbiense and R. maximum are probably best. R. Ponticum is extensively used in Europe, but it is not hardy enough for the north.
Rhodotypos. See [Kerria].
Rhubarb. See [Rheum].
Seeds, layers, suckers, root-cuttings, and cuttings of green or ripe wood. Suckers are oftenest used.
Rhynchosia. Leguminosæ.
Propagated by seeds and division.