Peony propagation

Peonies, both woody and herbaceous, have been cultivated in gardens for centuries. Numerous species grow naturally across temperate regions of the world, and centuries of cultivation have produced a wide variety of cultivated varieties. Gardeners propagate peonies using various techniques, which have evolved and improved over time. Both woody and herbaceous types are considered challenging plants to propagate and grow, and they have never been inexpensive. In fact, some of the newer varieties can reach very high prices.

Peonies are propagated in ways that do not quickly yield large numbers of new plants. As a result, only a small percentage of growers worldwide engage in propagation. Occasionally, some sellers present themselves as growers but rather re-sell mature or partially grown plants obtained from specialized producers.

Peony Propagation Methods

Peonies can be propagated either by seed (generatively) or through various vegetative methods. However, for cultivated varieties, only vegetative propagation is used, as seeds do not produce offspring identical to the parent plants. Many botanical species produce few seeds and readily cross-pollinate when grown near other species. In addition, many cultivated varieties are sterile and do not produce seeds at all.

When seeds are produced, they can be used to grow a mix of new, diverse plants. This applies to both woody peonies and herbaceous perennial types.

Propagation by Seed (Generative Propagation)

Peonies produce seeds of varying sizes, some as large as beans, with thick, tough seed coats. While these coats protect the seed, they also make germination slow and difficult. Once dried, seeds can remain dormant in the soil for a year or more before sprouting. Shortly after maturation, seeds develop germination inhibitors – hormones that prevent immediate sprouting. This natural mechanism ensures seeds remain viable until conditions are favorable.

Gardeners need to understand and manage these processes to successfully grow new peonies from seed. There are two main sowing methods:

1. Fresh (‘Green’) Seed Sowing:

This method uses seeds collected immediately after maturation, before the seed coat hardens or inhibitors develop. If sown in summer while fresh, the seeds often germinate by the following spring. This mimics natural conditions: seeds fall among leaf litter, experience warm summer temperatures that initiate germination, then enter a cooler autumn/winter phase before sprouting in spring.

2. Dried Seed Sowing:

For seeds that have dried and hardened – collected later in summer or even the following year – a special treatment is required. The seed coat is carefully scarified in several places to allow water penetration. Large quantities can be processed mechanically, while small batches can be sanded by hand. Seeds are then soaked in water for 24–48 hours before sowing, covered with a substrate, and placed in a lightly shaded area to maintain moisture.

Sowing temperatures should range from 25–30°C for at least one to two months, allowing moisture and heat to break down inhibitory enzymes. Germination continues over the cooler autumn and winter months. Very low winter temperatures may pause this process, but spring warmth resumes it. Uneven germination is common due to variability in seed maturation or inhibitor levels; some seeds may sprout the first spring, while others take two more years.

In controlled laboratory or greenhouse conditions, natural temperature cycles can be simulated to accelerate germination. Each of the two phases – warm summer and cooler autumn/spring – generally requires at least two months, though in nature, each may last three to four months without hindering germination. Extremely low winter temperatures are not essential but seeds remain dormant during winter in natural conditions.

Growing flowering peonies from seed typically takes several years. The speed depends on how closely ideal growing conditions are simulated. Natural, eco-friendly cultivation takes longer than forcing growth with heavy fertilization or artificial climate control, and peonies rarely bloom before two to three years.

Vegetative Propagation

The simplest method of vegetative propagation is division, though it produces the fewest new plants and is primarily used for herbaceous peonies. Plants in this group develop new growth buds at the root crown over time, which can be separated and grown into independent plants. Some species or varieties produce buds more quickly than others; in certain cases, it may take several years before a bud is strong enough to be used as a new plant.

When a well-established, mature plant is available—sometimes several decades old—it can be dug up entirely, including its deep and robust roots. Soil is removed with water or brushing to clearly expose the root structure, rhizomes, and buds. The plant is then divided with sharp, sturdy tools, ensuring each new section has roots and at least one visible bud.

This method is used to propagate herbaceous peonies during their dormant period, from early autumn to early spring in milder climates, for both professional and hobbyist growers.

When the soil is frozen, division is not possible. For professional purposes, mature plants can be dug up in autumn, with roots stored in cold storage over winter to produce bare-root seedlings for spring planting.

In vitro Tissue propagation

Peonies—both herbaceous and woody—can also be propagated using laboratory methods, such as tissue culture. This approach is particularly useful for slow-multiplying herbaceous varieties or new cultivars that need to be quickly produced in large quantities. From a single plant, thousands of new seedlings can be generated within one or two years.

Seedlings are then acclimated for life outside the laboratory or greenhouse. Even so, they generally require at least two more years to flower. For woody peonies, tissue culture can also accelerate propagation, but many cultivars grown this way may develop weaker roots, resulting in poorer growth and shorter lifespans.

Different cultivars of Paeonia lactiflora can be propagated by division or tissue culture. Some herbaceous peony species and their derived cultivars can also be propagated more quickly than by standard division using root cuttings. Dormant buds on the roots are activated when the roots are cut into short segments a few centimeters long and placed shallowly in soil. Seedlings produced this way still require a considerable period before they flower.

Woody peonies can also be propagated by cuttings, but this method requires precisely controlled temperatures and high humidity, which are difficult to maintain. Success is never guaranteed, and obtaining suitable cuttings is limited and labor-intensive, making the method inefficient. Consequently, tissue culture has largely replaced cuttings in modern practice. Although tissue culture is complex and sometimes yields imperfect results, it is much faster and more reliable.

Propagation via layering and air layering is now of limited value for woody peonies, but it remains useful for home gardeners and amateur cultivation. Before the development of tissue culture, professional growers also used layering, though it produced only a small number of new plants.

Grafting woody peony cultivars onto the root crowns of vigorous, healthy wild species is an old propagation method reserved for specialists, as it requires significant skill and expertise. Despite being partially overshadowed by modern tissue culture techniques, grafting remains valuable – plants produced this way often command high prices. Many woody peony cultivars do not develop strong roots on their own, so grafting is essential for producing robust, vigorous plants. However, only a limited number of new plants can be propagated using this method.

Breeding and Propagation of New Peony Cultivars

The search for new peony cultivars begins with sowing seeds obtained from spontaneous or controlled crosses. From the large number of seedlings, careful selection, record-keeping, trait analysis, evaluation, vegetative propagation, naming, registration, and often patenting follow. Only after this process are new cultivars introduced to the market. Developing a new peony cultivar typically takes at least a decade, and often much longer.

Traditionally, vegetative propagation was slow, meaning it took decades for a cultivar to reach widespread use. In recent decades, laboratory propagation using tissue culture and climate-controlled greenhouses has dramatically shortened this process, allowing rapid multiplication of genetically identical plants and the production of large numbers of seedlings for the market.

However, other essential steps—such as selection, evaluation, and the growth of a young plant into a flowering specimen—cannot be accelerated. Breeders carefully protect their work before registration or patenting to prevent competitors or novelty hunters from stealing genetic material and propagating it in laboratories.

New peony cultivars can also arise through spontaneous or induced mutations and other forms of genetic manipulation. Regardless of the methods used, every new cultivar must still undergo vegetative propagation before reaching gardens, public plantings, or commercial cut-flower production. Even with modern technologies, it still takes several years to grow a flowering peony plant from a new cultivar.

Text by Jožica Golob Klančič, MSc of Horticulture and Landscape architecture

Photos by Mojca Rehar Klančič, MSc of Agronomy