Plant growth retardants mainly include Chlormequat Chloride, Prohexadione calcium, Paclobutrazol, Uniconazole, etc. These retardants achieve the purpose of delaying plant growth by inhibiting the growth of plant subapical meristems, while not affecting the growth of apical buds. Their effects can be relieved by active gibberellins, which is the fundamental difference between them and growth inhibitors. When using these retardants, attention should be paid to adding surfactants to increase the application effect, and their application effect is strictly restricted by concentration and period, and it is not advisable to change the concentration or mix them at will.