Winter pruning has an important impact on the growth and shape of Platanus trees. If winter pruning is not carried out in a timely and reasonable manner, it may lead to disordered tree shapes, long main branches with fewer leaves or low dense growth, greatly reducing its ornamental value and shading effect. Timely and appropriate pruning can make the tree shape majestic and upright within a short period, making the branches and trunks evenly distributed, side branches numerous and symmetrical, leaves dark green and lush, while enhancing the tree's natural immunity.
Winter shaping and pruning for Platanus trees can be performed from late autumn when the leaves fall, the soil freezes, and the tree enters dormancy until early spring before the sap begins to flow. For newly planted young trees, when the trunk height reaches 2.5 to 3 meters, it should be pruned back, which is called "defining the trunk." Based on an overall assessment of the entire tree and a decision on future cultivation direction, start by cutting vertical branches and drooping branches, then cut diseased insect-infested branches, crossing branches, weak branches, inward-growing branches, and branches that affect traffic facilities. Finally, leave 3 to 4 strong main branches. The selected main branches should facilitate future shaping, have strong growth momentum, and moderate spreading angles. After selecting the main branches, prune them back at about 30 to 40 centimeters from the base. The cut should be smooth without damaging the bark, and apply wound dressing agent at the cut to prevent pest invasion and water evaporation. Smoothing the wound also promotes the formation of callus tissue, aiding in wound healing and preventing bacterial infection. Wound dressing agents can include grafting wax, white coating agent, tung oil, or paint.
Every 3 to 4 years after the growth of young trees, a major trunk pruning should be carried out during winter. Generally, the 3 to 4 main branches retained during the first pruning can remain unchanged, and 1 to 2 strong small branches can be kept on each main branch. When pruning these small branches, leave them at a length of 20 to 30 centimeters. The side branches on the small branches can be retained based on specific circumstances. If the communication lines near the tree are not high, only the 3 to 4 main branches shortened during the first defining of the trunk can be retained. This reduces the overall height of the tree while increasing the light penetration through the branches and leaves, neither affecting its growth nor preserving a good tree shape.
For already shaped Platanus trees, comprehensive pruning should still be conducted annually in winter. Pay attention to cultivating the dominance of the main branches, removing diseased insect-infested branches, vertical branches, overlapping branches, overly dense cluster branches, and side branches. Shorten excessively long main branches to stimulate the sprouting of branches and leaves at the base of the main and side branches, preventing baldness and ensuring a thick leaf canopy layer.
Platanus trees have strong budding abilities and are very tolerant of pruning. If pruning is done reasonably, the tree can maintain an aesthetically pleasing shape. If pruning is not reasonable, corrections can be made promptly during the next pruning session to achieve the desired tree shape.