China in addition to Xinjiang, north and south provinces and regions are distributed, especially in Yunnan, Tibet and Sichuan, the most species for the world distribution center of the genus Rhododendron. Rhododendron species, habits vary greatly, but most species produced at high altitudes, like cool, humid climate, evil heat and dryness. Requirements for humus-rich, loose, moist and acidic soil with a pH value between 5.5 and 6.5. Some species and horticultural varieties are more adaptable, resistant to drought, barren, soil pH between 7 and 8 can grow. However, it grows poorly on clayey or poorly permeable soils. Azalea has certain requirements for light, but does not tolerate exposure to the sun, summer and fall should have deciduous trees or shade shelter from the scorching sun, and often spray the ground with water. Rhododendron tresses generally in the spring and fall, with spring tresses mainly. The optimal growth temperature is 15 to 20 degrees Celsius, the temperature is more than 30 degrees Celsius or less than 5 degrees Celsius growth stagnation. There is a short period of dormancy in winter, and later with the rise in temperature, the flower buds gradually expand, generally cultivated in the open ground in March to May flowering, high altitude areas as late as July to August flowering. In the north in the greenhouse cultivation. 1 ~ 2 months to bloom. Rhododendron resistant to pruning, hidden buds are very easy to sprout after stimulation, which can be used to control the shape of the tree, reinvigorate the tree. Generally in May before pruning, the new shoots, the year can form buds, too late will affect the flowering. Generally before and after the fall sprouting of new shoots, can still be lignified. If the formation of new shoots is too late, winter is susceptible to frost damage. Evergreen or deciduous shrubs.

Cultivation and management

Commonly used seeding, cuttings and grafting method of reproduction, but also can be pressed and planting. Sowing, evergreen azaleas are best sown as they are picked, and deciduous azaleas can also store seeds until the following spring. When the temperature is 15 to 20 degrees Celsius, about 20 days seedling. Cuttings, generally in May to June to select the current year's semi-woody branches as spikes, set up shade after insertion, at a temperature of 25 degrees Celsius or so, 1 month can be rooted. Western azalea rooting is slow, about 60 to 70 days. Grafting, western azalea propagation using more, often shoot splitting, grafting time is not restricted, rootstock with two-year-old azalea, survival rate of more than 90%. Wild azalea and cultivated species of azalea, eastern azalea, summer azalea can be potted, can also be planted in the ground under the shade conditions. Western azalea all rows of potted plants, culture soil mostly with black mountain soil, with peat soil, yellow mountain soil, leafy soil, loose leaf soil and cinder, sawdust and other formulations of culture soil, as long as the pH value between 5.5 ~ 7.O, well-drained, rich in humus, can be used. Potting is usually done in April or November. Rhododendron root system expands slowly, l to 2 years old is suitable for 3 inch pots, 3 to 4 years old with 4 inch pots, every 3 to 5 years to change pots, while pruning the root system. Watering, according to weather conditions, plant size. Potting soil dry and wet and growth and development needs, flexibility, water quality alkaline, with tap water, it is best to store in the tank l ~ 2 months. mid-April out of the room, is at the peak of growth, the amount of water required; rainy season, to prevent stagnation of water; July to August high temperature season, evaporation is large, with the dry with the watering, midday, evening, but also to the ground, the foliage spraying to cool the temperature; early November into the room, if the indoor heating, the growth of the still thriving, the need for water is still large, especially at the time of flowering and tresses, and the water is still large. Still big, especially when the blossoms and tips, need more water; if the indoor heating is not slow growth, 3 to 5 days of watering once can be. To thin fertilizer, 2 to 4 years old seedlings, in order to accelerate the formation of the plant, often through the plucking, plucking buds to promote the development of new branches. After the plant molding, mainly cut off the diseased branches, weak branches and overlapping disordered branches, all to thinning mainly.

The main points of propagation: can be sown, cuttings, grafting and pressing and other methods of reproduction.

Maintenance points

One, environmental conditions : Cultivation of rhododendron is best to have two kinds of indoor and indoor environment. Indoor environment is used in winter. Yangtze River Valley, indoor as long as there is a certain amount of light and ventilation, generally do not have to add heat. In the north, where winters are extremely cold and dry, medium-temperature (around 15 ℃) greenhouses are appropriate. Outdoor sites, summer and fall use, to mud is good, avoid concrete. The site should be spacious, ventilated and shade, the top to build shade, cover with reed curtains or borrow natural shade shelter, light transmission rate of 30% or so is appropriate, avoid sunset.

Second, potting soil requirements: Azaleas like loose, permeable, well-drained, humus-rich acidic soil, PH value of 5.0 - 6.0. If you use clay or alkaline soil, it is difficult to live. Especially the summer azalea and azalea, non-mountain soil can not be. Mountain soil should also be transformed, and at present, three kinds of formulated culture soil are usually used. (1) 7 parts of mountain soil, 1 part of dry moss grass clippings, 2 parts of dry leafy soil, 1 part of dry fertilizer mixture. (2) 3 parts of mountain soil (topsoil), 3 parts of horse manure, 3 parts of leafy weeds, 1 part of human urine, layered heap, after 1-2 years after the sieve standby. (3) 3 parts of mountain soil, 3 parts of leaf-rotted soil, 4 parts of garden soil, 2 parts of sand, and add 50 grams of jaggery residue, bone meal per pot.

Three, pot selection: Cultivation of azalea pots, according to the use of the general use of clay pots and alabaster pots two. Clay pots are good ventilation and water permeability, conducive to the growth of the root system, production units are cultivated with this pot. Molded azalea, especially the shape of the azalea, for indoor and outdoor furnishings, generally planted in beautiful and elegant alabaster pots, alabaster pots fine texture, rich color, beautiful shape, can double the ornamental value. Alabaster pots less permeable than clay pots, in planting, should be in the surrounding basin wall pads with broken tiles ( old tiles ) so as to facilitate drainage. Select the size of the pot depends on the age of the plant, generally 4 - 6 years old plants with 5 inch pots; 7 - 10 years old plants with 6 inch pots; 11 - 15 years old plants with 8 inch pots.

Four, improve the quality of water: watering azaleas is best to use rainwater, followed by river water, pond water. If you use tap water, you should store the water for 1-2 days to let the chlorine evaporate before using it. Add 0.2% ferrous sulfate when using, and water it once every 7-10 days during the growing season, and use it frequently to make sure the soil is acidic.

V. Fertilizer and water management: Azalea likes shade and humidity, and should not be too dry. It needs more water during the flowering period. In winter, azalea has entered the dormant period, not much water, generally every 4 - 5 days watering once, preferably before and after noon on sunny warm days. Watering should be done around noon on sunny and warm days, depending on the dryness of the potting soil. In March, the azalea root sprouting, water demand increases. Summer azalea growth and development is a little late, the amount of watering should be less than the spring azalea. Generally every 2 days in the morning moderate watering once. April - June azaleas bloom one after another, branches and leaves also began to draw hair, water demand is larger, generally should be in the morning or evening watering once a day. July - early September high temperature and dry season, watering once in the morning and once in the evening, the amount of water should not be too much, and at noon in the foliage and ground spray to maintain a moist environment. From mid-September to November, the weather is gradually turning cooler, for the growth of azalea adaptation period, in order to prevent the extraction of autumn, to enhance the winter cold resistance, the amount of watering should be appropriately reduced. Generally every other morning watering 1 time, keep moist can be. Rhododendron prefer fertilizer, generally use rotted cake fertilizer, fishmeal, broad beans or purple dolomite, etc. After rotting watering, avoid using human feces and urine. Out of the room until the buds spit flowers, every 10 days to apply a thin fertilizer, concentration of 15%, **** 2 - 3 times, to promote the old leaves turn green, sprouting new roots. After the flowers, in order to promote the development of branches and leaves, in mid-May to early July fertilization 5 - 6 times. If it rains continuously, dry fertilizer can be applied. Before entering the room, the azalea's growth is about to stop before, should be fertilized 1 - 2 times.

Sixth, outdoor shade: before leaving the room to the flowering of the desirable more sunshine; flowering period, the midday should be a short period of shade, light transmission rate of 60%; in June to early July during the rainy season, it is the azalea leaves branching period, as much as possible to see the sun. However, in case of strong sunlight, 9 a.m. to 4 p.m. should also be shaded to prevent burning of new leaves. Mid-July to early September, every day from 8 a.m. to 5 p.m. to shade, to prevent the hot sun. After September, the fall growing period can shorten the shade time, generally from 10 a.m. to 4 p.m. shade, after October should see more sunlight. After the plastic surgery, cut off the long branches, sick and weak branches, deformed branches, damaged branches.

Seven, shaping and pruning: Azalea grows slowly, generally let the natural growth, only in the flower after shaping, cut off the long branches, weak branches, deformed branches, damaged branches. The main method of control of terminal leaf roller is to catch and kill by hand, and the larvae or pupae can also be killed by spraying 40% of Lekomat emulsion 2000 times or dichlorvos 1500 times.

Red spider can be controlled by 1000 times of dicofol. The army mating insect can be controlled by 1500 times of Lego or dichlorvos. The most common disease is brown spot, can be 800 times Tobramycin or equal amount of Bordeaux liquid control.