Cultivation techniques of Rhododendron in North China

Rhododendron is one of the ten famous flowers in China, known as "the west of the flower". It has many species, luxuriant flowers and luxuriant leaves, and is mainly distributed in the southwest provinces of China, which is mainly divided into four categories: rhododendron, eastern rhododendron, summer rhododendron and western rhododendron, among which the western rhododendron is the most beautiful flower. In recent years, with the rise of flower industry, rhododendron has been widely cultivated in the north.

1. Reproductive technology

① cuttage propagation is the most widely used propagation method in rhododendron cultivation. Generally, the robust semi-lignified new branches, about 5-8 cm in length, are cut off from May to June. The lower leaves are cut off, and 2-3 pieces of top leaves are retained as cuttings. The base of cuttings is best dipped in solutions such as indolebutyric acid or ABT rooting powder, and then cuttings are cut in loose, aerated, acid soil rich in humus. The temperature is kept at 20-25 ℃. Shade and often spray to moisturize to promote the germination of new roots

② twig split grafting for valuable varieties that are difficult to survive, such as rhododendron, cut off the twig about 3cm to 4cm as scion, cut the base into a wedge with a sharp knife, use cuckoo as rootstock, use twig split grafting, then tie it with plastic film under the shade shed, and cover the scion and rootstock together with plastic bag to keep moisturizing.

2. Fertilizer and water management the growth and development of rhododendron requires acidic soil (the soil PH value is 5.5-6.5) because the northern soil is mostly alkaline, so the basin soil needs to be mixed with humic soil such as rotten pine needle soil. The root system of rhododendron is whisker-shaped fine root, which has strict requirements on fertilizer concentration and water quality. Phosphate fertilizer can be applied once a month to promote the growth of branches, leaves and buds before flowering in spring. The mixed fertilizer based on nitrogen and phosphorus was applied once and twice after anthesis. Phosphate fertilizer was applied twice at the bud stage from September to October. In the growing period, flowering period, more requirements for fertilizer and water, dormancy in winter, slow growth in summer to control fertilizer and water, in order to prevent rotting roots. Azaleas like humid and cool environment, the northern climate is dry, should be timely watering and spraying, in order to maintain high air humidity. It is better to water flowers with alum, fertilizer water and Rain Water. If you use commonly used water, add a small amount of ferrous sulfate and vinegar. Watermelons or tomatoes can also be cut into small pieces, which also has a good effect on improving the quality of the soil and flowers.

3. Shaping and pruning to accelerate the blooming of plants, rhododendrons often promote new branches by picking their hearts, and those who cluster around flowers and affect their shape can sparse buds earlier, which not only makes the flowers big and fresh in the current year, but also helps the plants to grow and bloom in the coming year. Rhododendron has strong germinating power, and its branches seriously affect plant growth and development, reducing its ornamental and commercial properties, so it needs to be adjusted by pruning. Pruning is generally carried out after blooming in spring and autumn, cutting off withered branches, oblique branches, long branches, disease and insect branches and some cross branches to avoid nutrient consumption and make the whole plant blossom and full.

4. Florescence control rhododendron flower bud differentiation in autumn, through cold storage and heating treatment, the florescence can be artificially controlled. To make the cuckoo blossom early, it can be cultured in a greenhouse, the temperature is controlled at 20-25 ℃, and water is often sprayed on the branches and leaves to maintain a relative humidity of more than 80%, so that it can blossom after a month and a half. In order to delay the flowering of rhododendron, the cuckoo that formed buds should be kept at low temperature all the time, kept at 2: 4 ℃, watered when the pot was dry, moved outside in summer and autumn, and could blossom after 2 weeks.