Moderate mowing of lawn can control the height of lawn grass, inhibit the upward growth of lawn grass, stimulate the tillering at the base and improve the lighting conditions of the leaves at the base of lawn grass. If lawn maintenance personnel do not understand the biological characteristics of lawn grass, and the pruning method and timing are not properly selected, it will not only destroy the uniformity and ornamental effect of lawn, but also reduce the utilization value of lawn. Improper pruning will also bring weeds and epidemic diseases and insect pests, and even lead to the weakening of lawn grass growth and even death.
I. Biological characteristics of turfgrass
1, the biological growth point of turfgrass is low and protected by leaf sheath. The process of cutting grass will not cut off the growing point of lawn grass, but will reduce the top advantage after cutting off the stem tip, which is beneficial to tillering at the base of the plant. Because the growing point is protected by leaf sheath, it can also reduce the physical damage to lawn grass caused by trampling or mechanical rolling. Lawn grass has many small leaves, flat and slender leaves and upright leaves. Lawn grass is mostly low, tufted or stolon-like, with strong coverage. Turfgrass is a perennial plant, which is in the vegetative growth stage for a long time. It needs pruning or other measures to delay or prevent the transition from vegetative growth to reproductive growth.
2. Variety characteristics of lawn grass Generally speaking, when the height of new lawn plants reaches 10 cm, it needs pruning, but different grass species have different suitable pruning heights, so the recommended pruning height is appropriate. Cool-season lawns, such as tall fescue and Kentucky bluegrass, grow upright and have high pruning height. Warm-season grasses, such as Zoysia japonica and Bermuda grass, crawl on the ground, with low growth points and low pruning height.
Second, the role of lawn mowing
Inhibition of lawn growth and pruning can promote the germination of new branches at the base growth point of lawn grass, promote lateral growth and increase lawn density. Removing shadows and pruning too many leaves are beneficial for sunlight to reach the base of lawn, improving the photosynthesis of leaves at the base and providing more assimilation products for the growth of roots. The transfer of assimilated products to roots can provide organic nutrients needed for respiration, improve the activity of lawn roots, promote their absorption of water and nutrients, and improve the elasticity and smoothness of lawns. Controlling the growth period of turfgrass Under the induction of specific light conditions, turfgrass began to transform from vegetative growth to reproductive growth, and the ornamental value of turfgrass weakened after flowering. With proper pruning, tillering will be stimulated while removing inflorescences.
Third, the principles and methods of lawn grass pruning
1. Pruning method Repeated pruning in the same place and the same direction will cause the grass leaves to grow in the same direction, which will make the lawn grow unevenly and weaken the lawn. When pruning, it is necessary to change the pruning direction to prevent the lawn mower from pruning in the same direction and rolling the soil, and ensure the vertical growth of lawn grass, and maintain a relatively consistent pruning surface after pruning. Finally, fine cutting can be carried out along the direction of 45 or 90 from the initial cutting direction to ensure more uniform trimming.
2. Determination of pruning height Pruning height refers to the height of plants after lawn pruning, and the pruning height of different lawns is different due to their genetic characteristics and uses. Pruning can not achieve the purpose of control, too low will affect the vitality of lawn grass, slow down the recovery of growth, lead to bare ground and even lead to weeds. The height of turfgrass is directly related to the depth of root system. If the pruning is too low, the root system will be shallow, so the lawn is more vulnerable to drought stress and needs more water to maintain the normal growth of the lawn, and it is not easy to turn green after water stress. Similarly, too low pruning will also cause maintenance difficulties. Under the condition of low pruning, weed seeds in the soil will get more light and weed seedlings will get better growth conditions, which will lead to weed breeding. Although the grass roots above the ground are also deep, plants have strong tolerance to drought stress, and excessive pruning will also bring adverse effects to the lawn. Too high a lawn is not only unsightly, but also reduces the ornamental value of the lawn, especially resulting in sparse grass, reduced tillering ability and even diseases and insect pests. When determining the pruning height, environmental conditions should be considered in addition to variety factors. On the shady lawn, the pruning height of lawn grass should take the upper limit of its recommended pruning height range, so that more leaves can be kept on the aboveground part and more sunlight can be obtained, thus providing more assimilates for the root system and ensuring the high vitality of the root system. Different lawn uses have different requirements for pruning height. The rest lawns are often trampled, so the pruning times should be reduced and the pruning height should be increased appropriately. For sports lawns such as football fields, the trimming height should be appropriately reduced, and the golf course should be trimmed lower. The newly planted lawn must be trimmed when it reaches the upper limit of recommended height, otherwise it will cause the lawn to sleep or hinder its growth. Before pruning, make sure the soil surface and leaves are dry. For the newly planted lawn roll, because the root system has not been fully restored, the lawn can not be fixed, so be very careful when pruning, so as not to cause the lawn to turn over or move. Pruning principle: the principle of 1/3 should be mastered in lawn mowing. For a tall lawn, it is impossible to trim it to the required height at one time. Every time you mow the grass, you should cut off 1/3 leaves, so that the remaining leaves can carry out normal photosynthesis and supplement assimilation products for the roots. If it is excessively pruned once, the overground part will not provide enough assimilates for the root system, which will hinder the growth of the root system, and the lawn will die due to lack of nutrients. If the lawn grows too vigorously, the pruning height should be raised as much as possible, and then trimmed at the height of the normal pruning range after three or four days, so as to avoid excessive pruning of mature leaves, causing mild burns and overgrown weeds. When the lawn grows high enough, the lower leaves are blocked for a long time and can't see the sun, which has adapted to the shady environment. Cut off the upper leaves, and the lower leaves will be exposed to the sun, which will cause the leaves to burn due to excessive light.
3. Determination of mowing frequency The mowing frequency of lawn grass depends on the growth speed of lawn grass. In warm season, centipedegrass needs the least pruning times, followed by Zoysia punctata, Zoysia tenuifolia and Zoysia japonica, and Bermuda grass and carpet grass need the most pruning times. Festuca tenuifolia and Festuca arundinacea in cool-season grass need less pruning times, while other grass species need more pruning times. The application of fertilizer, especially nitrogen fertilizer, has a great influence on the growth rate of lawn. Generally, the higher the amount of nitrogen fertilizer, the faster the lawn grows and the higher the pruning frequency. In addition, excessive use of nitrogen fertilizer will also weaken the resistance of lawn grass to pests and diseases. Therefore, the rational use of nitrogen fertilizer should not only ensure the demand for nitrogen in lawn, but also prevent excessive application of nitrogen fertilizer. At the same time, combined with the results of soil testing, phosphorus, potassium and iron should be used together to reduce pruning times and ensure the healthy growth of lawn grass. Pruning frequency is also related to the growing season of lawn. Generally, the cool-season lawn grows faster in spring and autumn, with more pruning times, and grows slower in summer, with less pruning frequency. Warm-season turf grows faster in summer, slower in spring and autumn, and the pruning frequency decreases. Whether it is cold-season grass or warm-season grass, the root system grows slowly and its activity decreases in cold climate, which can not provide necessary nutrition for the aboveground parts. Therefore, the lower limit of the suitable pruning height should be taken during pruning to reduce the nutrient consumption of the aboveground parts. In a certain range, irrigation amount is related to the growth of lawn grass. The more irrigation, the more times the lawn is mowed. On the contrary, under drought conditions, plants grow slowly, with small growth and less pruning times. Don't mow the lawn when it has just been watered or the soil is wet, so the mowed lawn will appear uneven, and the cut grass clippings will easily gather and cover the lawn, which will suffocate the lawn due to insufficient light and ventilation.
4. Disposal of cut grass The cut grass is left on the lawn. Although the nutrients in the cut grass clippings can be returned to the lawn, which can improve the drought situation and prevent the growth of moss, they should usually be cleaned up in time. Otherwise, the accumulation of grass clippings on the lawn will not only make the lawn look unsightly, but also suffocate the grass below because of insufficient light and ventilation. In addition, the decomposed grass clippings will produce some toxic organic acids with small molecules, which will inhibit the activity of lawn roots and weaken the growth of lawn. The remaining grass clippings are also conducive to the breeding of weeds and easily lead to the prevalence of pests and diseases. Under normal circumstances, grass clippings should be cleaned up in time after each pruning. However, under high temperature conditions, if the lawn itself grows healthily and there is no disease, grass clippings can also be left on the lawn surface to reduce soil moisture evaporation.