How to Propagate Peonies? A Detailed Guide to Common Propagation Methods

Peonies can be propagated by sowing, division, or grafting. Division and grafting are the most commonly used methods, though sowing and cuttings are also possible. The suitable time for transplanting is from late September to early October, and it should not be done too early or too late. The sowing method is mostly used for breeding new varieties.

Propagation by Division

Division propagation of peonies was already widely adopted in the Ming Dynasty. The specific method is as follows: dig up an entire large, vigorously growing peony plant, and separate it from the junctions of the root system's texture. The number of daughter plants divided from each plant depends on the size of the original plant; large ones can be divided into more, small ones into fewer. Generally, every 3-4 branches form one daughter plant, with a relatively complete root system. Then mix a small amount of sulfur powder with mud. Apply and rub the mud evenly over the wounds on the roots, and they can be replanted separately. The time for division propagation is during the period from the Autumn Equinox to Frost's Descent each year, and it is best done at the appropriate time. At this time, the air temperature and soil temperature are relatively high, and the peony is in a semi-dormant state, but there is still a fairly long period of vegetative growth, so division and planting have a less severe impact on root growth, and after division and planting, some new roots and a small number of plant buds can still grow. If division and planting are done too late, root growth in that year will be very weak, or no new roots will form, and in the following spring the plant will develop even more weakly; weak roots cannot tolerate drought and the plant is prone to dying. If division is done too early, when the air temperature and soil temperature are relatively high, it can still grow rapidly and is likely to cause autumn sprouting. The mother plant used for peony division is generally a robust clump. On the mother plant used for division propagation, root suckers should be retained as much as possible, and all roots on the new seedlings should be kept, so that after 5 years of growth they can produce more new seedlings. Such divided seedlings are easy to establish after planting and grow relatively vigorously. The more roots retained, the more vigorous the growth.

Propagation by Grafting

Peony grafting propagation is divided into two types according to the rootstock used: one is wild peony; the other is herbaceous peony root. The commonly used peony grafting methods mainly include three types: cleft grafting, side grafting, and bud grafting. Cleft grafting uses herbaceous peony root as rootstock; because herbaceous peony roots are soft and have no hard core, they are easy to graft, and the roots are thick and short with sufficient nutrients, so growth in the early stage after successful grafting is vigorous. If peony root is used for grafting, the xylem is relatively hard, making grafting more difficult, but the lifespan is longer. The best time for grafting is generally from late September to early October each year. The rootstock used is a thick, pest- and disease-free herbaceous peony root with a diameter of 2-3 cm and a length of 10-15 cm. Side grafting is a method of top grafting to replace the head and improve varieties. It uses the many branches on inferior peony varieties or 8-10-year-old medicinal peony plants to graft excellent varieties of different colors. The grafting time is from early July to mid-August. First select a peony plant with excellent variety, a robust plant, and no pests or diseases, and cut soil sprout branches emerging from the ground, or current-year short branches 5-7 cm long; it is best to use short branches with 2-3 strong buds as scions. Leave one petiole on the scion. After selecting the scion, make a slanted cut on the back of the lower bud of the scion into a horseshoe shape, then make another slanted cut on the other side of the horseshoe shape into a wedge shape, so that after grafting both sides can contact the cambium tissue between the xylem and phloem, which makes survival easier. Before and after side grafting of peonies, except during the rainy season when irrigation is not applied, the suitable moisture for normal plant growth should be maintained. Bud grafting is an effective method for peony propagation and for cultivating multiple varieties and multiple flower colors on one plant. The bud grafting time is from May to July. It is best to do it on sunny days. Its methods include the bark patch method and the bud replacement method. The bark patch method involves cutting a rectangular or shield-shaped incision together with the xylem on the current-year branch of the rootstock, then cutting off the axillary bud of the scion together with the xylem into a bud piece of the same size and shape as that on the rootstock. Then quickly press the bud piece onto the incision on the rootstock and tie it tightly with plastic string. The bud replacement method involves removing the axillary bud together with the cambium at the grafting site on the rootstock, keeping the intact bud embryo on the xylem, then peeling off the axillary bud of the scion in the same way, quickly fitting it onto the bud embryo of the rootstock, taking care that the two match, and finally tying it tightly with plastic string. After grafting, the plant should be watered, the soil loosened, and fertilizer applied in a timely manner to promote healing.

Propagation by Cuttings

Cutting propagation is a method of using peony branches, which readily produce adventitious roots, to propagate new plants, and is one of the asexual propagation methods. The method is to first cut off the branch to be used as a cutting, separate it from the mother plant, and then insert it into soil or another substrate to cause it to root and become a new plant. For peony cutting propagation, the branches used should be current-year soil sprout branches emerging from the peony roots, or, when peonies are being shaped and pruned, branches with solid stems, plump terminal buds, and no pests or diseases should be selected as cuttings, 10-18 cm long. Peony roots are fleshy roots and prefer a dry environment, avoid moisture, and tolerate drought. Therefore, the nursery bed should be chosen in a ventilated, sunny place, and a raised bed should be built for raising seedlings. When cutting, after planting one bed, irrigate that bed, watering it thoroughly each time.

Propagation by Sowing

Sowing propagation is the use of seeds to reproduce offspring or to select and breed new varieties, and is a sexual propagation method. Before sowing, the soil must be fairly carefully prepared and disinfected; the land should be deeply plowed and finely worked, and sufficient base fertilizer should be applied. Then build small beds 70-80 cm wide, and either hole sowing or drill sowing may be used. Sowing should not be too deep, with 3-4 cm as the limit; after sowing, cover with soil level with the bed surface. Then gently firm the soil and immediately water it thoroughly.

Propagation by Layering

The peony layering method is a propagation method that uses the principle that branches can produce adventitious roots. The branch is bent down or buried with soil on the plant without being separated from the mother plant, the soil is kept moist, and the buried part of the branch roots; it is then cut off and planted to become a new plant. It is likewise an asexual propagation method for peonies. This method mainly includes: the pot-nesting and soil-mounding layering method and the double-flat method.

Tissue Culture

Plant tissue culture propagation is based on the totipotency of plant tissue cells and uses peony embryos, flower buds, stem tips, young leaves, and petioles for in vitro culture. Generally, these materials are placed in 75% alcohol and soaked for 5-10 minutes, then immediately placed in sterile water for washing, then soaked in 5% Antiformin solution for 7-10 minutes for surface sterilization, then rinsed 3-4 times with sterile water, and finally placed on culture medium for aseptic culture. The basic culture medium is MS, and the other additional components mainly include: different concentrations or different combinations of indoleacetic acid, naphthaleneacetic acid, indolebutyric acid, gibberellin, hydrolyzed protein, and so on.