Pinching Technique for Robinia hispida: Promoting Multiple Blooming Cycles

Robinia hispida, also known as Jiangnan locust, under natural growing conditions blooms only once a year. A large amount of nutrients is devoted to shoot growth, and water sprouts can reach over one meter. When summer arrives, strong winds can blow the tender shoots off their growth direction, forming a lopsided crown. This not only reduces the ornamental value of Robinia hispida but also increases the workload of winter pruning. During winter pruning, many branches that have grown rampant for a year are removed or cut back as useless branches, and the cut-back branches will continue to grow rampant the following year.

By utilizing the characteristic of Robinia hispida's new shoots to grow multiple times, adopting the technique of pinching whenever new shoots appear, the vegetative growth of Robinia hispida is transformed into flower-promoting growth, enabling Robinia hispida to bloom multiple times each year, extending the flowering period and reducing the amount of branch growth. In this way, the crown of Robinia hispida becomes compact, the ornamental value is greatly improved, and the amount of winter pruning is also reduced.

When the first new shoot of Robinia hispida grows to about 5 cm, following the principle of retaining as many inflorescences as possible, pinch off about 1 cm of the shoot tip. After about one week, secondary new shoots will sprout from the first new shoot, and secondary inflorescences will emerge at the same time. When the secondary new shoots grow to about 5 cm, pinch again to promote tertiary new shoots and a third round of inflorescences. By repeating the above pinching technique, Robinia hispida can bloom more than five times. In the Qingdao area, repeated pinching can extend the flowering period of Robinia hispida to late July.