This towering rhododendron beside a carpark was like a house on fire. I have never seen such red rhododendrons before.
Rhododendrons are shrubs in the heath family (family Ericaceae) and are thus related to heathers, Kalmia (mountain laurels), blueberries and cranberries. Since almost all of these plants require acidic soil, they are often referred to as the family of acid-loving plants.
Rhododendrons are found chiefly in mountainous areas of the arctic and north temperate zones. In Japan, they can be found in the wild such as on subalpine to alpine zone of Hokkaido and northern part of Honshu in Japan, including the west and north slopes of Mt Fuji.
Rhododenrons usually have big, shiny, leathery evergreen leaves and clusters of large flowers in white, pink, white, or purple hues.
Japan has its own native mountain rhododendrons but the cultivation of garden rhododendrons has a long history with rhododendrons originating from China. Japanese rhododendron include: R. keiskei (Keisk rhododendron); R. metternichii (leather-leaf rhododendron); R. indicum (indica azalea); R. kuisianum (Kyushu azalea); R. linearifolium (spider azalea); R. mucronatum (snow azalea); R. degronianum ssp. yakushimanum; and the Satsuki and Kurume evergreen azaleas.
Care of Rhododendrons
Rhododendrons grow best in partial shade, since full sunlight tends to bleach the flowers. They need an acid soil with a pH of 5.0 to 6.0, well mulched with organic material. Mix garden loam with equal parts of coarse sand and ground bark or oak leaves before planting. Soil around the rhododendrons’ shallow roots must be kept cool and moist but well drained. All except leatherleaf rhododendrons transplant well in the spring, or in the fall if mild winter weather does not damage the shallow-rooted plants. Fertilize once a year after the plant blooms with a mixture of 5-10-5 and cottonseed meal. Prune rhododendrons after the flowers have faded to induce new growth. Most evergreen rhododendrons are propagated from cuttings rooted in sand or a mixture of sand and peat. Deciduous rhododendrons are propagated by seed, grafting or cutting.
Read more about Japanese Rhododendrons at Henning’s Rhododendron and Azalea Pages.