Osmanthus fragrans planted in the open field has a minimum temperature of -5℃ to -8℃ in the north. If the temperature exceeds this limit, osmanthus fragrans will be frozen to varying degrees. The general hibernation temperature is 0-5. Therefore, planting osmanthus fragrans in the open field in the north, we should choose the place facing the sun and lee, plus artificial cold protection measures, which can safely overwinter. Osmanthus fragrans is protected in winter. Every winter to the future, the trunk should be artificially tied with straw rope or wrapped with other warm materials to prevent general freezing injury. In the coldest three or nine days, the crown of osmanthus fragrans can be wrapped with transparent plastic film, and pay attention to leaving pores to let osmanthus fragrans spend the cold winter safely.
If Osmanthus fragrans planted in the ground is frozen without protective measures [this year's freezing damage is mainly caused by plastic sheets not being fixed, grinding leaves and branches, shivering with cold], certain rejuvenation measures should be taken according to the degree of freezing damage. For example, the leaves of osmanthus trees are freeze-dried, and the branches are not frozen to death. After the spring, you can pick the dead leaves manually and fertilize them with thin water. Appropriate amount of ferrous sulfate should be added when fertilizing (adjusting soil pH and promoting the green formation of leaves) to make the root soil environment acidic, which is beneficial to the germination and rejuvenation of osmanthus fragrans. If the branches freeze to death, artificially cut off the frozen branches, and then fertilize them with dilute water to promote their germination. If the whole osmanthus is frozen to death, it is necessary to cut off the frozen trunk at the top of the wedding festival, and then strengthen the management of water and fertilizer to make it grow new branches again. If possible, it is best to transplant new osmanthus at this time, so as not to affect the landscape. Digged osmanthus roots can be cultivated in greenhouse to form osmanthus bonsai.
The number of cuttings depends on the age and growth potential of the tree. Hundreds of years old trees should leave few or no branches, because their growth is weak. Young trees with strong growth potential can leave more branches appropriately. When pruning, we must first remove pests and diseases, excessive growth and cross branches. Then apply vaseline or Bordeaux solution to the wound to avoid pests and diseases and rain erosion.
2. How to prune in summer?
Osmanthus fragrans has strong germination ability and has the characteristics of naturally forming shrubs. It is shot twice a year, in spring and autumn respectively. If it is not pruned and germinated in time, it is difficult to cultivate tall plants, and it is easy to form the phenomenon of dense upper branches and sparse lower branches. When pruning, except for those who are not good because of the growth of trees and branches, we should give priority to thinning branches, only properly thinning out the peripheral branches that are too dense, and cutting off the overgrown branches and pests and diseases to improve the ventilation and light transmission conditions of plants. It is necessary to erase the sprouting branches from the base of the trunk in time to avoid consuming nutrients in the tree and disturbing the tree shape.
Plastic trimming
Pruning osmanthus fragrans is an important measure to cultivate single-dried osmanthus fragrans. Timely and reasonable pruning can make it ventilated and transparent, strengthen photosynthesis and reduce pests and diseases, so that osmanthus fragrans grows rapidly, its trunk is straight and its tree shape is beautiful. Mainly includes:
(1) When osmanthus fragrans with peeled buds germinates, the buds on the trunk and base can also germinate. The useless buds at the lower part of the trunk should be peeled off in time to concentrate water and nutrition, promote the development of the upper branches and form an ideal tree shape.
(2) Planting osmanthus fragrans with single stem by thinning branches. From the beginning of seedling raising, we should consciously cultivate the trunk straight, keep a certain height under the branches, and cut off useless branches. Generally, the height under the branches of osmanthus fragrans is about 1.5 meters.
(3) Cutting short, that is, cutting off the top branches that are growing too vigorously, so that the height of osmanthus fragrans is kept at about 3.5 meters, and the crown width is kept at 2.5 to 3 meters. When transplanting Osmanthus fragrans, in order to maintain a complete tree shape, it is not advisable to cut it forcefully, but only cut off dead branches, disease and insect branches, sparse overlapping branches, cross branches and thin branches, and control long branches.
Trim properly. Osmanthus fragrans has developed root system and strong germination. Mature osmanthus trees germinate twice a year. Therefore, in order to make Osmanthus fragrans flourish, it is necessary to prune it properly to maintain the physiological balance between reproductive growth and vegetative growth. Generally, it is necessary to cut off long branches, thin branches and branches of pests and diseases, so as to facilitate ventilation and light transmission, concentrate nutrition, and promote osmanthus fragrans to breed more and fuller flower buds, and then bloom luxuriantly.
Pruning of potted osmanthus fragrans should be done after autumn flowers. For plants with high trunk, hollow lower branches and bad tree shape, all the top branches can be cut off at 2/3-3/4 of the trunk height to stimulate new branches to grow at the lower part of the trunk. For plants with too large crown and "top-heavy" shape, you can cut off the branches that are too thick above and keep the branches below to balance the tree. Plants with too dense branches can be thinned to make the remaining branches flourish. Practice has proved that plastic pruning, especially heavy pruning combined with comprehensive management of water and fertilizer, has a good effect on improving the growth of osmanthus fragrans.
Fertilize soil or land
Apply base fertilizer before winter, mainly organic fertilizer; In early spring, quick-acting nitrogen fertilizer is mainly used, and fertilizers such as rotten bean cake, pig and poultry are mixed with water to promote the vigorous growth of new shoots; From the end of June to the end of July, quick-acting nitrogen fertilizer was mainly applied, and phosphorus and potassium fertilizer were combined to promote the growth of summer shoots. In management practice, the types and quantity of fertilization should be determined according to the growth potential of osmanthus fragrans. If the number of summer shoots is less than 10- 15%, it shows that the tree is weak, and the frequency and quantity of nitrogen fertilizer application should be increased. Fertilization should be arranged reasonably according to local conditions.