Rhododendron Simsii (Azalea) Profile

Written by Maggie

Dec 28 2022

Rhododendron Simsii (Azalea) Profile

Rhododendron simsii is a deciduous shrub, ca. 2 m tall; Rhododendron simsii has many ranches, branches thin and straight. Leaves are alternate, long elliptic ovate, apex acute, surface dark green, sparsely bristle, abaxially light green.  

Rhododendron Simsii Picture

Rhododendron simsii

Morphological Characteristics of Rhododendron Simsii

Rhododendron simsii is one of the most famous flowers in the world today. rhododendron simsii is a small shrub in the Rhododendron simsii family, some evergreen and some deciduous. Rhododendron simsii flowers are found throughout the temperate regions of the Northern Hemisphere. The Rhododendron simsii flower is beautiful. Tubular flowers, deep red, light red, rose, purple, white and other colors. When Rhododendron simsii flowers bloom in spring, the mountain is bright and bright, like the rosy clouds surrounding the forest, and is known as the "flower in the beautiful". The colorful Rhododendron Simsii flower evokes people's warm and beautiful feelings towards life, and it also symbolizes the prosperity of the country and the happy life of the people. That's why our people love Rhododendron Simsii.

A representative species of the Rhododendron simsii flower is commonly known as the "mountain red". It is almost all over the provinces of the Yangtze River basin, as well as Yunnan, Taiwan and other mountains and hills on the sparse forest or shrub.  


Rhododendron simsii is a deciduous shrub, about 2 m high; Branches, bracts, petioles and flowers all have brown flattened strigose.


Leaves of Rhododendron simsii are papery, ovate-elliptic, 2 -- 6 cm long and 1 -- 3 cm wide, apically acute, basally cuneate, strigose on both surfaces, abaxially densier. Flowers 2-6 clustered at branching tips; Calyx is 5-lobed, lobes elliptically ovate, 2 -- 4 mm long; Corolla of Rhododendron simsii is bright red or deep red, broadly funnelform, 4 -- 5 cm long, 5-lobed, upper 1 -- 3 lobes with deep red spots on the inner surface; Rhododendron simsii has 7-10 stamens, filaments puberulent below middle, anthers purple; Ovary and style are near base strigose, stigmas capitate.


The flowers of Rhododendron simsii are solitary or racemose, corolla campanulate or broad funnel-shaped, usually five-lobed, and can be red, yellow, white, purple, and pink, depending on the species. Rhododendron simsii flowers in April, while summer Rhododendron simsii flowers in May or June.Capsule, seed many and small.

When Rhododendron simsii flowers were in full bloom, the ancient people left many poems and beautiful and moving legends, and there was the custom of celebrating the festival with flowers. Rhododendrons are mostly shrubs or small trees, which have their own living habits and shapes due to different ecological environments. The smallest Rhododendron simsii are only a few centimeters high, cushion-like, ground growing. The largest is as high as a few feet, standing tall and spectacular.


Capsule of Rhododendron simsii ovoid, ca. 1 cm long, strigose.Indicator plant for acid soil. The leaves contain flavonoids (azalea alcohol), triterpenoids and ursic acid.

Ecological habits of Rhododendron Simsii

Rhododendron simsii flowers prefer acidic soils and do not grow well or at all in calcareous soils. Summer to sun shade, winter should pay attention to warm and cold. Avoid the scorching sun exposure, suitable for growing under the light intensity is not big scattering light, light is too strong, young leaves are easy to be burned, new leaves and old leaves coke edge, serious will lead to plant death. In winter, measures should be taken to protect Rhododendron simsii from cold in open field to ensure its safety

How to Grow and Care for Rhododendron Simsii

Environmental conditions

Rhododendron simsii flowers are best cultivated in both indoor and indoor environments. The interior environment is used in winter. Yangtze River basin, indoor as long as there are certain lighting and ventilation conditions, generally need not heating. Winter in North China is extremely cold and dry, so it is appropriate to use a greenhouse at medium temperature (about 15℃) for cultivation. Outdoor sites, summer and autumn use, with mud as the best, avoid cement. The site should be spacious, ventilated and shady, and the shade should be set up above, covered with reed curtain or by borrowing the protection of natural shade. The light transmittance of about 30% is appropriate, and the sun should not be exposed overnight.

The Soil Care

Rhododendron simsii flowers like loose, permeable, well-drained, humus-rich acidic soils with a pH of 5.0 -- 6.0. If you use clay or alkaline soil, it is difficult to live. Especially the summer cuckoo and the ocean cuckoo, not mountain soil.

Mountain soil is also modified, usually using the following preparation of culture soil.

(1) 7 parts of mountain soil, 1 part of dry carex cuttings, 2 parts of dry leaf rot soil and 1 part of dry fertilizer were mixed.

(2) Three parts of mountain soil (topsoil), three parts of horse dung, three parts of deciduous weeds, and one part of human excrement were layered and compacted. After 1-2 years, they were screened for reserve.

(3) 3 parts of mountain soil, 3 parts of leaf rot soil, 4 parts of garden soil and 2 parts of sandy soil were mixed and prepared, and 50 grams of sesame paste residue and bone meal were added to each pot.

Flowerpot Choice

Cultivation of Rhododendron simsii flower pot, according to the use, generally choose two kinds of mud pot and purple sand pot. Devon ventilation and good water permeability, conducive to root growth, production units are cultivated with this basin. The moulded Rhododendron simsii flower, especially the moulded Rhododendron simsii flower, is generally planted in the elegant purple sand basin for indoor and outdoor display. The purple sand basin is fine in texture, rich in color and beautiful in shape, which can increase the ornamental value. Purple sand basin permeability performance is not as good as the devil basin, when planting, should be in the basin wall pad with broken tiles (old tiles) so conducive to drainage. The size of the pot should be depending on the age of the plant, generally 4-6 years old plants with 5 inch pots; 6-inch pots for 7-10 year old plants; Use 8-inch basins for 11-15 years of reproductive plants.

Rhododendron simsii

Improve Water Quality

Rhododendron simsii flowers are best watered with rainwater, followed by river water, pond water. If tap water is used, it is advisable to store the water for 1-2 days to let the chlorine evaporate before use. When used, add 0.2% ferrous sulfate, water once every 7-10 days during the growing season, and use frequently to ensure that the soil is acidic.

Water Management

Rhododendron simsii is a wet person and should not be too dry. More water is especially needed during flowering. In winter, Rhododendron simsii flower has entered the dormant period and does not need much water. Generally, it should be watered once every 4 to 5 days, and it should be done around noon in warm and sunny days. Specific according to the basin soil dry water.In March, Rhododendron simsii flowers start to bud, which increases water requirements. The Rhododendron simsii should be watered less than Rhododendron simsii when the Rhododendron simsii grows later. Generally every 2 days in the morning proper watering 1 time. Rhododendron simsii flowers bloom gradually from April to June, and the branches and leaves begin to drain. Water needs a lot of water. Generally, water should be watered once a day in the morning or evening. 

Outdoor Shade

In the room before the flowering should see more sunshine; During flowering, shade should be carried out for a short time at noon, and the light transmittance is 60%; During the plum rains of summer, when Rhododendron simsii flowers are spawning, you should get as much sunlight as possible. But in case of strong sunshine, from 9 am to 4 PM should also shade, in order to prevent burning the new leaves. In summer, shade should be provided from 8am to 5pm every day to protect against the burning sun. After autumn, the autumn growing season can shorten the shade time, generally can be in the morning from 10 to 4 PM shade, after autumn, it is appropriate to see more sunshine. After plastic surgery, cut off long branches, sick and weak branches, deformed branches, injured branches.

The Plastic Clip

Rhododendron simsii flowers grow slowly. Generally, they are allowed to grow naturally. Only after flowers are reshaped, and long branches, sick and weak branches, deformed branches and damaged branches are cut off.

Disease Control of Rhododendron Simsii

Disease and insect pests of Rhododendron simsii were mainly controlled by prevention. Before germination of new shoots in winter and spring, flowerpots, soil and plants were sprayed with 600 to 800 times of topbucine solution or equivalent amount of Bordeaux solution for 2-3 times. After new bud germination, spray with 50% wetting carbendazim 600 times solution, once a week, continuously spray for 3 times; Midsummer season, easy to happen red spider, can use 50% dichlorvos emulsion 2000 times the liquid spray kill.

Species Taxonomy of Rhododendron Simsii

Frequent cultivated species in China are: rhododendron, summer rhododendron, western rhododendron, Yang Zhaoyu, Yinghong rhododendron, Ma Yinhua, Yunyin rhododendron.

There are about 900 species of Rhododendron simsii, of which about 850 species are produced in Asia, of which 530 species are found in China. Except for Xinjiang, Rhododendron simsii is distributed in the north and south of China. There are about 280 species in New Guinea and Malaysia, almost all of which are epiphytic.In addition, there are 24 species in North America, 9 species in Europe and 1 species in Oceania. There are many species of Rhododendron simsii, which are very different, including evergreen large trees, small trees, evergreen shrubs and deciduous shrubs.

Azaleas are deciduous and evergreen. Deciduous leaves are small and evergreen leaves are large. The colors of flowers are red, purple, yellow, white, pink, blue and so on. Rhododendron simsii is pleasant to cool, moist, cold resistance, more growth in the sea of 1000-1400 meters of the hillside, alpine meadow, forest margin, stone wall and swamp.

The Distribution of Rhododendron Simsii

Rhododendron Simsii is concentrated in the Hengduan Mountains of Yunnan, Xizang and Sichuan provinces.

China is the distribution center of Rhododendron simsii, with about 460 species, distributed in all provinces except Xinjiang and Ningxia. Southeast Xizang, southwest Sichuan and northwest Yunnan are the most concentrated producing areas, each accounting for more than 100 species. Yunnan alone accounts for more than half of the national varieties of rhododendron. Many countries in the world have introduced species from here. Rhododendron simsii is a large genus, there are about 900 species in the world, distributed in Europe, Asia and North America, and Asia is the largest, 850 species, of which there are 530 species in China, accounting for 59% of the world, especially concentrated in Yunnan, Xizang and Sichuan three provinces in the Hengduan Mountains area, is the birthplace and distribution center of the world rhododendron. Bhutan, Sikkim, Nepal, Myanmar, northern India in the Himalayas, there are also many species, Japan, Korea, the Soviet Union Siberia and the Caucasus only a few species.

Rhododendron Simsii Main Value

Rhododendron simsii can be grown in a pot or in shade. Its shape is beautiful and beautiful. The Rhododendron simsii tree planted in the garden should be cut into an umbrella shape to add fun and beauty. Rhododendron simsii is suitable for planting in moist and shady forest, rock, garden suitable for planting in trees, under the forest, stream, pool and lawn edge; In the shady side of the building can be used for flower hedge, flower cluster with planting.Some species can make bonsai.

Rhododendron simsii has developed roots and is a good water and soil conservation plant. Rhododendron simsii flowers and leaves, beautiful appearance, strong germination, pruning resistance, peculiar root pile, is an excellent bonsai material. In gardens, it is best to plant in clumps and patches by the edge of forests, streams, pools and rocks, and also to plant in scattered forests. Rhododendron simsii is also an excellent material for hedgerows and can be pruned and bred into a variety of shapes. The Rhododendron Simsii is very special.

Rhododendron simsii can be used as ornamental, medicinal or aromatic oil extraction, edible, bark and leaves can be made into baking glue, wood can be made into arts and crafts, etc.The branches, leaves and flowers of rhodium alba soaked retting system can be used as insecticidal.

Rhododendron simsii