What are the cultivation technique requirements for oleander?
1. Site selection and land preparation: choose a warm, humid climate environment, a sunny spot, well-drained, sandy loam soil.
2. Propagation methods: oleander propagation methods are simple, with a very high survival rate; commonly used are cuttings, layering and division, water rooting, etc.
(1) Cutting method: the cutting method can use either hardwood or softwood cuttings. Hardwood cuttings are done in early spring together with pruning of the seedlings; cut branches 15-20cm long, tie every 20 together, immerse in clean water at 20°C, with 1/3 immersed in the water, change the water frequently; after about 8 days the immersed part of the branches turns white and the top becomes sticky, then take them out and insert them into the seedbed. Or soak the branches in water for 30-40 days, and after they root, insert them into a sand bed, provide shade, and they will easily survive. In addition, soak the cuttings in a 0.1% potassium permanganate solution, or treat them with 0.001%-0.002% indolebutyric acid for 24h, then insert them into a sand seedbed and give a certain temperature. At 16-18°C, they will root in 20 days. Softwood cuttings are better done in late spring and early summer during the plum rain season; softwood cuttings can be rooted either in water or in sand, or first in water and then in sand; pay attention to shading, change the water frequently, keep moist, and with a water temperature above 18°C, they will root in half a month. After one month, move them into the seedbed to continue growing, and after 2 years they will bloom.
(2) Layering propagation method: layering propagation is divided into air layering and ground layering, carried out in March-April; air layering mostly uses potted plants. After 30-40 days they will root. Ground layering is mostly done in the rainy summer; take branches of the mother plant close to the ground, make a ring cut in the bark, then bury them in the soil; softwood layering can only be watered after 3-4 days, keeping it moist. If it meets the rainy season, they will root 7 days after layering; after rooting, cut off half, and in autumn cut off all, then carry out autumn planting or spring planting.
(3) Seed propagation: seeding is done in late spring; at a temperature of 18-21°C they germinate quickly. If large-scale propagation is not needed, division propagation is preferable.
(4) Transplanting: transplanting can be done in spring or autumn; transplanting in autumn and winter requires a soil ball. For large-scale propagation, division propagation is preferable. In the transplanting site, before planting, apply more pig manure, beans and other fertilizers, because oleander has a very strong ability to absorb fertilizer; for transplanting, plant one at a row spacing of 1cm-100cm; after transplanting, water thoroughly the first time. If transplanting in summer, besides carrying a soil ball, also appropriately thin out branches and leaves; in order to reduce leaf surface sprouting, during transplanting appropriately prune the branches with a messy tree shape and all the leaves (both soil-ball transplanting and bare-root seedlings are pruned).
3. Field management
① Intertillage and weeding: in the cutting seedbed, pull out weeds as soon as they appear.
② Topdressing: oleander has an especially strong preference for fertilizer; water with a dilute liquid fertilizer once every 10-15 days (pig manure, soybean cake, black alum).
③ Watering: water more in summer and less in winter.
④ In winter, potted plants are brought indoors, and in spring they are taken outside; red-flowered oleander has weak cold resistance, and during the seedling stage it needs to be wrapped with straw for cold protection.
⑤ Pruning: before budding in early spring, appropriately truncate the branches to make them sprout evenly; mostly follow the branching rule of one branch into three forks and three forks into nine shoots, so as to expand the upper canopy and create a full tree shape with dense branches and a robust tree form. For aging plants, to rejuvenate and renew them, use the strong pruning method of cutting back close to the ground to promote the sprouting of new branches.
4. Pest and disease control: pests and diseases are very few; aphids sometimes cause damage, and can be controlled by spraying a 1000-fold 40% dimethoate emulsion aqueous solution.