The planting seasons of plants in Central China, North China and the Yangtze River Basin are divided into spring, rainy season and autumn. Spring is divided into early spring and late spring. Planting in early spring from early February to late March is suitable for deciduous trees. Planting in late spring is from April to early May, suitable for evergreen trees, and long-term planting in rainy season. The rainy weather in the Yangtze River valley from June to July created conditions for plant planting. Plants are planted before dormancy in autumn, and plants enter dormancy from mid-June 1O to1late October 1 1, which is beneficial to the recovery of root growth. Except for planting in spring, rainy season and autumn, the rest of the year is called unsuitable planting season. Inappropriate seasonal planting is often limited by the project schedule and completion date, or green planting is carried out during surprise missions. In order to improve the survival rate, a series of technical measures are taken in the process of planting and maintenance to reduce the influence of inappropriate seasonal environment on the survival rate of greening planting.
First, the characteristics of unsuitable season planting
1, it is difficult to plant in the growing period (summer), because the average temperature is higher than 22℃, the sunshine time is long, and the fibrous roots (absorption roots) are damaged during the planting process, which makes the water metabolism of plants unbalanced; However, the large transpiration of leaf water makes plants lose water and reduces the survival rate. Therefore, it is necessary to reduce plant transpiration and replenish water during the growth period.
2. Planting in dormant period (winter): It is difficult, because the average temperature is less than 10℃, the sunshine is short, and the plants are in dormant period. Because the low temperature is easy to cause freezing injury, it is necessary to avoid planting in cold days, and pay attention to keeping warm after planting to prevent freezing injury.
Second, technical measures for planting in unsuitable seasons
1. Earthwork construction: The quality of earthworks is the key to the survival of planting. It is best to choose soil that is not polluted. However, large-scale greening needs a lot of earthwork and soil is in short supply. Earthwork excavated by municipal or foundation is often used. Before entering the earthwork, it is necessary to do excavation and reconnaissance to analyze the soil layer distribution and soil quality. Generally speaking, there are many impurities in topsoil above 1m, loess above 3-4m and deep soil below 4m. The soil lacks fertility, silt appears below 6m, poor air permeability and no fertility. Therefore, it should be analyzed according to the digging situation.
2. Large-scale greening often requires large-scale machinery to cooperate with construction, and bulldozers should be avoided. Due to the heavy weight of bulldozer, the air permeability of earthwork is poor after being pushed layer by layer, which affects the survival rate of planting. It is best to choose an excavator of 0.25-0.4 cubic meters, which has light self-weight and low mechanical pressure on soil. After molding, loosen the soil with a grab, recover it after loosening to increase the permeability of the soil, and then level it artificially.
3, the technical treatment of building seedlings:
(1) Root cutting treatment: determine the size of the mud ball according to the DBH of the tree. Generally, roots are cut in situ with DBH 8- 10 times in advance 2-3 years, and 0.00 1% NAA 0.5 kg is sprayed on the roots, then covered with soil, carefully maintained, and dug again when planting.
(2) Choose potted plants or basket-planted seedlings: For deep-rooted seedlings, it is difficult to dig up the soil balls completely because of less fibrous roots, such as pyracantha and wisteria, and it is not easy to survive when planted in unsuitable seasons. Pot planting or basket planting can be used to ensure the survival rate.
(3) Technical treatment of temporary seedlings: Due to the tight construction period, the selected seedlings cannot be planted in spring without root cutting treatment. Before budding, the roots should be cut and bandaged, sprayed with 0.00 1% NAA, and covered with soil, and then bandaged and dug when the seedlings are to be used. For succulent root plants, such as Magnolia grandiflora, fibrous roots are underdeveloped. When transplanting, the mud ball should be 10 times of DBH to minimize the damage to the root system. The mud ball is wrapped with double-layer hemp rope. In case the mud balls are lost during transportation.
(4) As you dig, transport and plant:
Digging (seedling raising): The size and quality of mud balls are the key to survival and recovery. The better the root system protection, the more conducive to the recovery of plant metabolic balance. Mud ball dressing must conform to the specified size, and the dressing should be tight and mesh. The waist should be complete, so that the clay ball will not come loose during transportation.
Seedling transportation: it should be shipped in time, and the source of seedlings should be organized as close as possible in summer. Before shipment, the seedlings should be watered and covered with shading cloth to prevent the plants from losing too much water during transportation. It is best to transport seedlings at night. After arriving at the site, handle with care to keep the mud ball intact. They should be stacked in a dark place and sprayed with water on the leaves.
Planting: Trees should be planted first, then shrubs, deciduous trees should be planted first, then evergreen trees should be planted, which should be shallow and not deep, so as to avoid plant suffocation and water accumulation. When planting big trees, you can put some gravel and middle soil at the bottom to increase soil ventilation. Pruning is an important link before planting, which can reshape and reduce the evaporation of nutrients and water in plants, remove weak branches, diseased branches, long branches, parallel branches, cross branches and drooping branches, and keep the tree perfect; Evergreen broad-leaved trees can peel off 50% leaves; Deciduous trees can erase old leaves and make them regenerate new ones. Spraying 500g O.00 1% nai acetic acid to the roots of big trees to promote the recovery of growth; And backfill nutrient soil in the tree hole and plant it by grouting if necessary.
Third, the maintenance measures after planting
After relocation, the roots of plants are damaged and their metabolism is unbalanced. How to restore their growth depends on "three-point planting and seven-point planting", especially in inappropriate seasons, which requires regular water spraying to keep the leaves moist. After the new leaves of big trees germinate, 0.0 1% urea is used for foliar fertilization to supplement the lack of root support. You can use shading cloth to shade the light when it is hot in summer. Tree trunks can be wrapped with straw ropes in winter. Wrap the straw rope with film to improve the insulation effect. If the temperature rises, take off the film to prevent boredom. Taking reasonable technical measures, careful maintenance and overcoming unfavorable factors that are not suitable for planting in season will definitely improve the survival rate.