Rhododendron 'Shinan' is a new variety of rhododendron.

Rhododendron 'Shinan', also known as tree-type rhododendron, alpine rhododendron, or foreign rhododendron, is one of the high-end potted flowers that have become quite popular in recent years. This variety was introduced from the Netherlands, Belgium, and other countries. Compared with common rhododendron varieties such as spring rhododendrons, summer rhododendrons, and Western rhododendrons, its flowers are large and densely clustered, looking like a big ball of flowers when in full bloom and giving a feeling of abundant blossoms. It is suitable for large and medium-sized potted cultivation and for decorating halls, restaurants, hotels, and other places with a magnificent effect.

Rhododendron 'Shinan' is a perennial evergreen shrub or small tree of the genus Rhododendron in the family Ericaceae. The plant is much branched, with a full crown and a compact shape; the leaves are alternate and densely clustered at the tips of the branches, elliptical or lanceolate, leathery and glossy, and some varieties also have golden yellow markings or margins on the leaf surface; the underside of the leaves is slightly lighter in color and densely covered with fine hairs. The inflorescence of Rhododendron 'Shinan' is a raceme-like umbel, with flowers borne terminally, often several clustered at the branch tips, forming a spherical shape when in full bloom, usually 15 cm to 20 cm in diameter, with some varieties reaching more than 25 cm; the flowers are bell-shaped, single or double; the flower colors are rich, including purple-red, red, pink, orange-red, peach-red, purple-blue, white, yellow, and many other colors. Its natural flowering period is from March to May, and with artificial forcing it can bloom earlier, from January to February, with the flowering period of a single plant lasting up to one month.

Rhododendron 'Shinan' is a temperate alpine plant. Most varieties originated in southwestern China and are mainly distributed in plateau mountainous areas at altitudes of 2000 m to 4500 m. Rhododendron 'Shinan' prefers a cool, humid, semi-shaded environment and has a certain degree of cold tolerance. The suitable growth temperature is 15°C to 25°C. It is not drought-tolerant, fears intense heat and scorching sun, and also fears waterlogging. Each year after the flowers fade, the spent flowers can be cut off, and after the flowering period ends, the branches can be cut back to promote the growth of leaf buds. Watering should follow the principle of "do not water if not dry, and water thoroughly when watering," avoiding both water accumulation in the potting soil and excessive drought. If the air is too dry, water can be sprayed on the plant and the surrounding environment to increase air humidity. During the growing season, apply decomposed alum fertilizer water once every 10 to 15 days, or sprinkle solid compound fertilizer on the surface of the potting soil and bury it shallowly so the roots can slowly absorb it.

The high temperature and heat of summer are extremely unfavorable to the growth of Rhododendron 'Shinan'. When the temperature exceeds 30°C, plant growth is inhibited, and when it exceeds 35°C, the plant will suffer heat damage to varying degrees. Therefore, in summer the plant can be moved to a ventilated, cool shade shed for maintenance, and attention should be paid to ventilation to avoid diseases in a stuffy, hot environment. When it is hot and dry, water can be appropriately sprinkled on the plant and the surroundings to lower the temperature and increase humidity. During the rainy season, avoid water accumulation in the potting soil to prevent root rot, and stop fertilizing at the same time. After autumn cools, normal water and fertilizer management can be resumed, and light should be appropriately increased. South China has high temperatures all year round, which is very unfavorable to the growth of Rhododendron 'Shinan'. Especially during the high temperatures of summer, poor care can easily cause death, so it needs to be moved to a cooler region for cultivation in order to get through the hot summer.

In winter, place Rhododendron 'Shinan' indoors in a sunny spot; it can tolerate a low temperature of 0°C. Therefore, in winter the growing temperature is best kept below 15°C to avoid excessively high temperatures that affect flower bud differentiation. Every 1 to 2 years, potted ornamental Rhododendron 'Shinan' should be repotted once. Repotting is done after flowering. The potting soil should be loose, breathable, rich in humus, well-drained, slightly acidic sandy soil. It can be prepared by mixing leaf mold or peat soil with vermiculite or river sand. The pH value of the potting soil should be adjusted to between 5 and 6.0.

Rhododendron 'Shinan' can be propagated after flowering by cuttings or layering, while large-scale propagation uses tissue culture. When potting new plants, do not press the substrate too firmly; let it breathe, and do not prune. Wait until the root system is well developed and the terminal buds begin to grow, then prune to promote branching and make the plant shape full and compact.

In a high-temperature and high-humidity environment, Rhododendron 'Shinan' is prone to stem rot and leaf brown spot disease, which can be prevented and controlled by spraying carbendazim or thiophanate. Iron deficiency and alkalinity in the soil can also cause chlorosis in the plant, which can be prevented by adding black alum (ferrous sulfate) when watering and fertilizing. Pests mainly occur in summer and autumn, such as red spider mites and lace bugs, and can be prevented and controlled by spraying a 1000-fold to 1500-fold dilution of 40% omethoate.