Generally speaking, pine and cypress trees cannot be pruned or reshaped only by natural means, and only diseased dead branches can be cut off every year. In some parts of the garden, there are also artificial body shaping. In large-scale greening and afforestation, it is worth noting the problem of "pruning", because the natural thinning process of pine and cypress is slow, and manual pruning is often needed. Cutting off the weak branches is conducive to ventilation and light transmission, reducing the infection rate of pests and diseases, and is conducive to the formation of good materials without knots, which can appropriately generate some firewood for the use of nearby residents. The problem is the amount of pruning. Many places are used to pruning a lot, leaving only a small crown, which is bound to seriously affect the growth of plants. How much should I trim? This is closely related to the growth characteristics of tree species. Plateau believes that moderate pruning of Japanese cypress and Japanese cedar has little effect on growth. Slobo did an experiment on Pinus densiflora, and the crown was trimmed by 30%, 50%, 70% and 90% respectively. Five years later, it was found that the height growth of 90% trees without crown was obviously weakened, while the height growth of 30% -70% trees without crown was only slightly different. From this point of view, it seems that quite heavy pruning can be carried out; Actually, it's not, because it has been observed that the height growth of trees has not decreased significantly after severe pruning, but the diameter growth of cadres has decreased significantly. For example, Young and Kramer studied loblolly pine, and Lehtpere studied Douglas fir and found this phenomenon. Therefore, according to the cultivation purpose, both the growth of tree height and the influence on the growth of trunk thickening should be considered when pruning. Luckhoff once found that removing 25% of the crown of conifers will not affect their height and diameter growth, while removing 50% of the crown will reduce the diameter growth, but will not reduce the height growth. Dahms also believes that for many conifer species, the crown of 1/3 can be removed, but the tree height growth and diameter growth have not been significantly reduced.

For conifers planted alone in the garden, except for those with special requirements for natural wind-induced morphology, most of them are dominant branches and grow slowly, so we should pay attention to carefully protect the trunk from injury.