How to Propagate Peonies by Division: Detailed Methods and Steps
The simplest way to propagate peonies is by division. It can be done between the Autumn Equinox and Cold Dew; if division is carried out during the growing season, the plants will grow poorly and may even die. Division in cold winter and spring also easily causes death.
When dividing, first dig up the plant (the whole plant). Because peony roots are relatively deep, dig some distance from the roots and dig deeper. Remove decayed branches and rotten roots, and use a sharp knife to split them naturally from the roots (or you can pull them apart by hand). Be careful not to damage the root buds; each division should retain an appropriate amount of root system and the tiller buds at the crown. Peony roots are thick and fleshy and break easily, so after digging them up, dry them in the shade for 1-2 days before splitting. If the main stem is a single stem or there are very few stems and there are no divisions to make, you can mound soil 10 cm high in spring and keep it moist, wait for new branches and new roots to grow from the base, and then divide them in the autumn of the following year; in this way there is no effect on the mother plant.
After division, it is best to apply copper sulfate or potassium permanganate solution to the wounds for disinfection, to prevent infection by diseases. Choose a suitable cultivation site (slightly higher terrain, well drained, cool, and fertile) and after digging the hole, spray some dichlorvos or similar chemicals to prevent pests from damaging the roots. When planting, straighten the roots; they must not be twisted. After planting, cover with soil and tread it firm, then water several times in succession so that the soil settles completely and fits tightly against the roots. In North China the weather is cold, so in the first year the plants must be protected for overwintering; wrapping the plants with 3 layers of old newspaper is enough. Before wrapping, first tie the branches together with straw rope; before tying, use shears to cut off the leaves, keeping part of the leaf stalks to protect the buds from being knocked off. Open them again in mid-to-late March of the second year.