Pruning of old perennial plants is usually done twice a year: one is to change pots in early spring, cut off dense branches, thin branches, diseased branches and overgrown branches from the base, and cut off the tops of remaining branches; Another time, after the flowers withered, before the new branches grew, the branches were properly thinned and the dead branches, over-dense branches and inner branches were cut off. The remaining branches should be about 30 cm long and the upper branches should be cut off. At the same time, all the lateral branches should be cut short to promote the germination of more new branches, thus forming more flower buds and ensuring vigorous flowering every year.
Old plants that have grown for 5-6 years should be pruned again, that is, only 2-3 buds are left on each retained branch, so that they can germinate new branches again, which is conducive to renewing the tree potential.