When the spring shoots germinate in 1 and February-March, apply 1 time fertilizer, and according to the strength of the tree, supplement some weak trees with quick-acting nitrogen fertilizer, and apply more appropriately to trees with many flowers; The amount of nitrogen fertilizer applied to strong trees and few flowers trees accounts for 10 ~ 15% of the total annual amount, which promotes the healthy growth of spring shoots.
2. When applying fertilizer for the second time, spray 0.3% urea solution several times after flowering and before fruit swelling to supplement the loss of nutrients in the tree after flowering and increase the fruit setting ability.
3. The third fertilization is in July and August, when the autumn shoots are sprouting and the fruits are expanding. This time, the amount of fertilization is large, with nitrogen fertilizer accounting for 40% of the annual consumption and phosphorus and potassium fertilizer accounting for 50% respectively. Two fertilization pits with a depth of 30-40cm are opened at the drip line of each plant to ensure that the autumn shoots are strong and the spring flowers are well differentiated.
4. Fertilize for the fourth time. After the fruits are picked in June 5438+065438+ 10, and before the temperature drops, apply them deeply again, and dig holes on the other two sides in autumn. The application rate of nitrogen fertilizer accounts for 40% of the annual consumption, and that of phosphorus and potassium fertilizer accounts for 40% respectively, with organic slow-release fertilizers such as green manure and residue fertilizer as the main ones.
Matters needing attention in raising potted lemons:
1. Seedling cultivation and pot culture: there is a large amount of cultivation in the south, so grafting should be adopted for propagation; There is little planting in the north, mainly cutting, or buying grafted seedlings. The root system of lemon has high requirements for water, nutrients and soil. Potted soil should be made into water-permeable, breathable, water-retaining and fertilizer-retaining, slightly acidic culture soil. The time of loading and changing pots can be in autumn or early spring, which can be flexibly mastered according to the local climate.
Second, light and temperature: Lemon is a light-loving plant, but if the sun is too strong, it will grow poorly. Plants usually need to be replaced at noon. The annual average temperature suitable for growth is above 65438 05℃, and the optimum growth temperature is 23℃~ 29℃. If the temperature exceeds 35℃, plants will stop growing, and if it is -2℃, they will freeze to death. Lemons generally don't need to be cooled in summer. They enter the room before the first frost and leave the room after Qingming, so they can spend the winter safely.
Third, watering and fertilizing: Lemons need more water in their growth and development, but too much water is not easy to rot their roots. Generally speaking, spring is the time when the buds germinate and the leaves unfold. The pregnant buds are in full bloom and should be watered properly. In summer, with strong sunlight and high temperature, more water is needed. But it should be timely and appropriate, otherwise it will cause fruit loss. Autumn is the period when autumn shoots grow and fruits expand rapidly, so there must be enough water. The late autumn and early winter are the stage of flower bud differentiation, and the basin soil is dry. Lemons like fertilizer. In the growing period, in addition to applying sufficient base fertilizer on pots and changing pots, we should also adhere to the principle of applying thin fertilizer frequently. The frequency and amount of fertilization should be determined according to the growth and phenology.
Fourth, pruning methods: pruning is generally divided into winter scissors and summer scissors. In winter, pruning should be based on the principle of "removing density and keeping sparse, removing weakness and keeping strong", and cutting off dead branches, short-cut weak branches and long branches without initial effect. In summer, the main branches of the unfruitful trees are cut short, and as a result, the summer branches on the trees are erased, and the decaying branches in the middle and upper parts of the crown are cut short.