The growth pattern of the tree peonies is the same as that of the Central Plain peonies, and the annual cycle is composed of a growth period and a dormant period. There are two growth peaks for the middle roots of the long growth period. The first growing peak is in early spring, when the temperature of the 20 cm deep soil layer is stable at 4-5 °C, and the roots begin to move and sprout new roots, which is basically synchronous with the sprouting of some of the above-ground shoots. With the temperature rising, there is a gradual increase in activity; and when the flowers come to a high temperature after their maturity, the roots are very weak and in a semi-dormant state.
After autumn, with the temperature decreasing, the root system enters a second peak period of growth, not only where a large amount of nutrients are stored, but also where a large number of new roots are formed, often, the upper parts of the ground have already fallen into a state of hibernation and new roots remain unformed. In contrast, roots grow more and are more important in autumn than in spring. The traditional breeding and cultivation of peonies in the autumn season takes advantage of the characteristics of the root system so that it can produce a large number of new roots before it goes to sleep in winter, in order to make use of the water and nutrients it absorbs from the soil, enable the plants to recover and establish life as soon as possible.
Likewise, before rooting out in early spring, it is also true that they are transplanted. Before it starts to bud in the spring and before it starts to sprout, there is only a high survival rate and the tree recovers. However, if the plants are replanted after the spring buds have germinated and begun to grow, by the time the roots are already active, they will cause damage to the roots, in particular to the new roots that have already been produced, and miss the period during which they grow, loss of balance between the roots and the above-ground branches, resulting in a dramatic decrease in the survival rate. Therefore, it is advisable to replant Tree Peony in spring sooner rather than later.