The latest course on planting techniques and methods of rhododendron

Rhododendron bushes are distributed in all provinces except Xinjiang, especially in Yunnan, Xizang and Sichuan, which is the distribution center of rhododendron in the world. There are many species of rhododendron with different habits, but most of them are produced in high altitude areas, like cool and humid climate, and hate hot and dry.

Land selection and preparation

The site should be warm and moist, not too strong, cool climate, fertile soil, acid soil rich in humus, neutral soil with pH below 7 or pH=5-6, good drainage and ventilation.

Reproduction method

1. Seed propagation: most rhododendrons can bear fruit and collect seeds, only double petals are not fruiting. General seed maturity from October to January each year, when the pericarp from green to yellow to brown, the top of the fruit split, seeds begin to scatter, at this time should be harvested at any time. The final cracking browning is collected, put in a well-ventilated place to cool, make it naturally crack, and then remove the fruit shell and other impurities, put it in a paper bag or cloth bag, and store it in a cool ventilated place. If there is a greenhouse, the germination rate of sowing with picking is high. General sowing time from March to April, use pot sowing, because the seeds are small, wash the inside and outside of the basin, dry in the sun, sterilize and disinfect the soil, and install a basin with good permeability, moist and fertile acid soil rich in organic matter. In order to produce seedlings evenly, the seeds are mixed with some fine soil, sprinkled into the basin and covered with a thin layer of fine soil, and the watering method is used to infiltrate the basin into the basin. Put the basin on the front windowsill and cover it with a layer of glass or plastic film, in order to increase the temperature in the basin. After the seedling is unearthed, the covering time is gradually reduced, because the seedling is tender and small, pay attention to temperature change, sudden high and low change, strong light irradiation. The seedlings grew very slowly, and only 2-3 true leaves grew from May to June. At this time, the first transplanting was done in the room, the row spacing was 2-3cm, the seedling height was 2-3cm (about November), one big seedling was transplanted in the 10cm pot, and three small seedlings were planted. Use a fine spray can to water and light fat water. The greenhouse came out in the spring of the second year after sowing and was maintained in the shade. In the 13.3cm pot in June, the plant was 20cm high in the third year, and several branches also had flower buds. In the 16.7cm pot, the pot was changed year by year according to the size of the plant.

2. Cutting propagation: cutting is the most commonly used propagation method of rhododendron. Except for a few that can not take root, cutting can survive, easy to collect, easy to operate, and can retain the excellent characteristics of the variety. It can be cut for one year, and the best time is from May to June, followed by August to September. However, due to different varieties and different times, western cuckoo from late May to early June, rhododendron in early June, eastern cuckoo and summer cuckoo from mid-June to late June.

Selection of ① cuttings: cuttings can be selected for robust growth, free from diseases and insect pests, new shoots, semi-mature branches, lignified in the current year, and terminal branches outside the crown are the best. In principle, the mother plant has 3 new shoots, one as cuttings, 5 cuttings as cuttings, and the lengths are 5-7cm, 6-8cm, 8-10cm, respectively, and the over-long branches can cut off the top tips and remove the lower leaves. Leave 4-5 leaflets at the upper end and insert them as you pick.

② pot insertion method: wash and disinfect the basin, load the basin soil, fill the bottom with coarse-grained soil 1 beat 3, install 2 stroke 3 fine soil, drill holes, insert the cuttings into 1 inch 2-1 stroke 3, spacing 3cm, and water the cuttings with a fine hole spray pot.

③ insertion method: 15-20cm high and 80-l00cm wide surrounded by bricks, filled with coarse-grained soil and fine soil, the method is inserted in the same basin.

The above two methods should be under semi-overcast conditions. Build a shade shed to prevent the side sun and hanging curtains, keep the air humidity at 85%, pay attention to the management of moisture, always keep the cuttings fresh, do not lose leaves, so that you can take root in a month.

3. Grafting propagation

① connection: rely on the connection is more troublesome, after the survival of the appearance is not very beautiful, large-scale production is not suitable. The method is: in the growing season, select the scion and rootstock, in the appropriate part, smooth no node, each cut one knife, the length of the cutting surface is 3-4cm, and the depth is as deep as xylem. Align the two cambium, fasten the wound with a plastic bag, heal the wound for 4-5 months, cut off the scion from the mother, cut off above the interface of the rootstock, and turn it into a separate plant. The method is sure of survival and will soon become a tree with quick results. If it is not alive, it will not lose much to the plant.

② twig split grafting: the split grafting method is mostly carried out in May-June, with exuberant plant growth, many scion resources, moderate old and tender, rapid healing, and the survival rate is more than 90%. Rootstock selection, cuckoo cutting for 2 years, terminal bifurcation, scion with high ornamental value, disease-free and pest-free 3cm long scion, with 3-4 fine leaves on the top, all the lower leaves removed, cut into a wedge-shaped length of 0.5-lcm, cut off at the base of the new shoot of the rootstock at 2-3cm, and cut a knife in the center, which is a little longer than the cutting surface of the scion. Insert the scion to match the cambium on one or both sides. Tie it tightly with a plastic bag, cover the scion and the interface with a plastic bag, and tie a transparent bag at the bottom of the interface to prevent rain and keep the temperature. Usually keep the temperature in the bag, prevent direct sunlight, give some fat and water, cut off the sprouts of the rootstock in time, and remove the bag after 2 months.

Ventral grafting of ③ twigs: from mid-May to late May, rhododendron was still taken as rootstock and obliquely cut to xylem at the base of 6-7cm. The length of scion was 0.5-lcm, but the front was long and short, the long side was inserted inside, the short one was facing outward, the cover was well cut, the cambium was aligned, bagged and placed in dry shade.

4. Striping propagation: striping propagation is mostly carried out between May and June, which is divided into two methods: one is high-altitude striping, the other is low striping method.

① high-altitude pressing: select 2-3-year-old branches, cut a ring in the appropriate part, deep to the xylem, width 0.5cm, remove the skin, then put the made bamboo tube, long 8cm, diameter 2-3cm, one side with nodes, split from the middle, according to the diameter of the plant, dig semicircular holes, two semicircular bamboo tubes are covered in the cut. The tube is filled with acidic soil and watered to keep the soil moist. After 3 months, many fibrous roots grow inside, which can be cut off from the mother plant and cultivated in a basin.

② low-pressure propagation: low-pressure propagation is to make use of the sprouting branches of rhododendron planted in the ground, cut into rings in appropriate parts, remove the skin, and bury them in the soil. After 3 days, they are watered to keep the soil moist. After 3 months, the whisker root is found to grow, separated from the mother plant, and cultivated in the pot.

Field management

1. Soil treatment: at present, the ornamental rhododendron in garden is mainly potted, which is beneficial to meet the ecological conditions of different varieties. In cultivation, the requirement of soil is mainly acidic soil, and pH must be less than 6. No matter what kind of soil is used, it is necessary to carry out soil disinfection, full ripening, fermentation and alternating treatment of high and low temperature before cultivation, and it can only be used after one year. Among them, the best soil is forest humus soil, or self-prepared pine needle soil, with withered branches and leaves, adding a small amount of horse dung and sheep dung, and after picking it up, add fertile soil at the bottom of the mountain root. Add withered cake, human dung, pig dung, chicken and duck manure, calcium superphosphate, etc., plus 1x3 sandy loam, Huangshan soil, rotten leaf soil (litter, add manure) followed.

2. Transplant the upper basin and change the basin: before transplanting, the basin has no water hole, cross-cover it with several tiles, fill a layer of coarse-grained soil, then fill the fine soil every other year, plant a seedling in the middle of the basin to stretch the root, add soil to the rhizome, compaction, shake the basin to flatten the soil surface. Spray small, until the pot flower dripping water, after 7-10 days to cover the basin stage, before and after the room, should be placed in the greenhouse semi-shady place. The reason for changing the pot is that after the plant grows up, it can not meet the ecological conditions, so it is necessary to change the new culture soil, take off some shrinking soil from the old pot, stretch the surrounding roots, cut off the diseased roots, and operate as above. It is usually changed every 2-3 years. Large plants for 3-5 years, extra-large can not be changed, topdressing and other technical measures are applied to the space of azaleas to keep the relative humidity above 70%.

3. Watering: Rain Water, river, lake, pond and fish culture are the best for cuckoo watering. Alkaline water, well water and tap water are prohibited. In fact, the temperature of the well water is similar to that of the air. The tap water should be dechlorinated and volatilized for several days. Alkali water and sulfuric acid are added to correct pH. The amount of water should be different according to different growth stages, and the dormancy period should be less. Cuckoos in the south of the Yangtze River bloom from November to February and from March to June, and their vigorous growth should be watered more, watered once a day in sunny days, and replenished in some evenings. During the rainy season, pay attention to drainage, check every hour from July to August, and water the basin when it is dry. At the same time, the leaves are sprayed, watered in winter morning, watered in summer morning, and watered in spring and autumn except noon. In the indoor heated greenhouse, once every 2-3 days and 4-5 days without heating, the temperature rises in late February, the flower buds begin to swell, the leaf buds sprout, and the amount of water increases appropriately.

4. Fertilization: there are base fertilizer, long-term hoof, nail plate, bone powder, cake fertilizer, dung, etc., which are mixed with soil when pots are put on or changed. Topdressing fertilizer uses human manure, chemical fertilizer and quick-acting fertilizer. Cuckoos should be fertilized with different fertilizers at different growth stages. Apply more phosphate fertilizer before flowering to promote flowering, large flowering, thick petals, good color, long flowering period, once every 10 days, 2-3 times. Stop fertilizing during flowering. After flowering, in order to restore the tree potential, promote the shoot to grow leaves, apply nitrogen fertilizer, stop growing in the high temperature season (July-August), it is not easy to apply fertilizer. Before entering the room in autumn is the bud stage, apply more phosphate fertilizer, once every 7-10 days, and stop fertilization in winter dormant period. The principles of fertilization should be mastered: fertilizer should be fully mature, apply thin fertilizer frequently, and it is forbidden to apply fertilizer on leaves, in sunny days, when the basin soil is dry, in the evening, and the next morning.

5. Pruning: in order to maintain the beautiful appearance of the azaleas, it is necessary to prune too many branches and growing branches, buds, buds and other parts every year. When the rhododendron tree grows to a certain height, remove the top bud, control the height and germinate lateral branches. After picking the heart, many lateral branches grow, showing a whorled shape. The lateral branches grow to a certain height, and then pick the heart. Secondary lateral branches germinated. Bud peeling: when the bud grows to a certain extent, remove the tip of the bud to prevent the flower from blooming too much to waste nutrients. At the same time, the adventitious buds should be erased. In order to maintain the beauty of the tree shape, we should strengthen the tree potential, renew the branches, adjust the ventilation conditions, and cut off those weak branches, diseased branches, withered branches, crossed branches, overlapping branches, overdense branches and long branches from the base. The old plants should be pruned and rejuvenated, and the branches can be left and 30cm left or right to cut off the upper part before the new buds germinate in early spring. Can not be cut at once, carried out in stages, each cut 1 beat 3-1 hit 5, cut short, 3-5 years to complete. This does not affect flower appreciation, and careful management and fertilization after pruning can keep the plant growth prosperous for a long time.