In May peonies are the absolute stars in the bed and inspire with opulent flowers. Here you can read everything you need to know about planting and maintaining peonies.
Profile of peony:
Scientific name: Paeonia officinalis
Plant family: peony family (Paeoniaceae) ;formerly buttercup family (Ranunculaceae)
Other names: common peony, garden peony
Planting time: May to August for plants, root-plants in autumn
Flowering period: April to June
Location: sunny to partially shaded
Soil quality: heavy, loamy, nutrient-rich, humus-rich
These information are for temperate climate!
Use in: rock garden, cottage garden, Japanese garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 8-10 (-12 °C / +15 °F to -1 °C / +35 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of peony
Plant order, origin and occurrence of peony
The genus of peonies (Paeonia) includes perennials, subshrubs and shrubs. The perennial and shrub peonies, sometimes also called tree peonies, are of comparable importance in garden culture. The genus that formerly belonged to the buttercup family (Ranunculaceae) now forms its own family of plants, the peony family (Paeoniaceae). There are 32 species worldwide, all of which come from Europe and Asia, with the exception of two native to the west coast of North America. Peonies have been in cultivation for a long time as garden plants. The most important European species is the common or garden peony (Paeonia officinalis) native to southern European mountain regions, while tree peonies (Paeonia suffruticosa hybrids) and Chinese peony (Paeonia Lactiflora hybrids) have been shaping garden culture in China for 2000 years. Their types of origin come from the mountain forests there and partly also from steppe regions of the temperate and subtropical climate zone. The varieties of North America are the California Peony or Wild Peony (Paeonia californica) and the Brown’s peony, native peony or western peony (Paeonia brownii).
The plants are named after the Greek god Paean / Paieon. According to legend, he used the peony to heal the wounds of the god Pluton, which Heracles had inflicted on him in the battle for the city of Pylos. The common peony used to be of great importance as a medicinal plant. Although it is slightly toxic in all parts of the plant, it was used, among other things, to treat gout. Since its medical effectiveness could not be proven, it is no longer important in today’s medicine.
Characteristics of peony
Peonies grow cluster-like and upright and, depending on the type and variety, reach a maximum of 40 bis 110 cm (16 to 44 in) for perennials varieties and 100 bis 180 cm (40 to 72 in) for shrub varieties. They form bulbous storage roots with overwintering buds just below the surface.
Shrub peonies form strikingly thick-growing and weakly branched, upright shrubs. The largest varieties mostly come from the group of the so-called Rockii hybrids. They can be over two meters (6 ft 8 in) high and almost twice as wide in old age. The plants grow quite slowly and have strikingly large buds that sprout very early in the year.
A very young group of peonies are the so-called intersectional hybrids, also called Itoh hybrids. It is a cultivation between perennial and shrub peonies. They have herbaceous shoots, but grow more vigorously than the Chinese peony hybrids and have larger flowers.
The flowers of the perennial peonies sit on rather sturdy stems, which are covered with unpaired, often coarse, alternate leaves up to the top. The young shoots in the spring are usually marked dark red.
The leaves of the shrub peonies are alternate, usually double pinnate and light green to blue-green.
Perennial peonies bloom about a month before the real roses, depending on the weather, usually from late April to early May. The flower colors cover the entire spectrum from white to yellow and light pink to dark red and the shapes vary from simple bowl-shaped to densely filled. With some varieties, the stamens are also converted into short petals, which gives the flowers an anemone-like appearance.
The flowers of the shrub peonies usually appear from mid-May and are significantly larger than those of the perennial peonies: Diameters of over 25 centimeters (10 in) are not uncommon for the Rockii hybrids.
After flowering, peonies form noticeable, sometimes felty, follicles, in which the seeds are hidden. These can be over a centimeter (0.4 in) in size.
Peony – cultivation and care
The location should be in full sun to half shade. However, most species cannot tolerate strong root pressure from large trees.
These characteristics characterize the ideal location:
- sunny to partially shaded
- humic, loose soil, rich in nutrients
- fresh-moist to moderately dry and without waterlogging
- ideally a slightly acidic pH of 5.5 to 6.5
In contrast to most other garden plants, peonies prefer mineral, rather humus-rich soils. They like to grow on slightly heavier, loamy and evenly moist, well drained substrates, but are quite adaptable if the soil is not too dry.
When planting, there is an important basic rule: plant perennial peonies flat, plant shrub peonies deep. The reason: Perennial peonies often only form leaves and no flowers if they are too deep in the ground. Shrub peonies are grafted on roots of the perennial peonies and must be planted so deep that the grafting union is about three fingers wide underground. It is important that it has its own roots, because it cannot form a permanent connection with the perennial peony and so sooner or later it starts to take over. It is also important that you mix humus-rich soils with lots of sand or clay granulate. In addition, do not choose a too warm, sheltered location for shrub peonies. Otherwise, the shrubs sprout very early and are at risk of late frost.
Well-rooted shrub peonies can also take stronger pruning measures down to the old wood, but this is usually not necessary. Even without regular pruning, the shrubs form a balanced crown with many flowers. In addition, shrub peonies are very long-lived: specimens over 100 years old are known from China. In the case of perennial peonies, you can remove the old stems in late winter.
As long as a peony is in the rooting stage, watering is required. As deep rooters, the plants have penetrated so deep into the earth after 3 to 4 years that they independently supply themselves with water. Therefore, water freshly planted peonies in the first few years when it is dry.
Check with your finger that the top 2 cm (1 in) of the soil have dried. If this is the case, please water directly onto the root disc without causing waterlogging. At the time of bud formation, the water requirement is particularly high.
A nitrogenous fertilization is not beneficial for peonies, they then often become susceptible to fungal diseases. A potassium and phosphate-stressed fertilizer of organic origin (no compost) added in early spring promotes vitality and budding for the coming year.
Shrub peonies are prone to breakage in snowy winters. As a precaution, you should tie the somewhat brittle shoots loosely with a rope in autumn. So they can support each other. A support in the form of a perennial holder can also be advisable for some perennial peonies.
Shrub or perennial peonies can be propagated vegetatively and generatively. There are several options for vegetative propagation. The plants are grafted, mainly by fostress grafting, cut grafting, bud graft, chip grafting and historical wedge grafting.
Cuttings can also be cut. It is also possible to propagate by division, by layer and by air layering. Meristem multiplication is also successful, but mostly only for specialists. In vegetative propagation, identical plants are created. The situation is different with generative propagation. Sowing does not necessarily result in identical plants.
This is how to do it:
Greenhouse conditions are ideal for the propagation by cuttings. You need constant temperatures, good lighting conditions and high humidity. The use of rooting hormones (e.g. willow water) is also recommended. The right time for cutting is after flowering, in June / July.
- The cuttings need a long time to form roots
- The difficulty is to keep the soil slightly moist until then. It must not dry out and not be too wet. Many cuttings die of thirst or rot.
Older plants are particularly suitable for division. The best time is autumn. To do this, the root must be dug out. You can cut, saw or tear them apart. It is important that all sections have at least one to three buds (eyes). Without the eyes, the plant cannot sprout. To prevent rot, a wound closure agent should be used. The wounds are usually quite large.
- Share older plants
- Dig out the root completely
- Split with a sharp tool, i.e. spade or saw
- Alternatively, tear apart
- Pieces need at least one bud, better are more
- Use wound closure agents
- Dig in again
Ground layering works quite well, but it takes time. For this purpose, a lower branch of the peony is carefully bent to the ground and fixed there. You have to be very careful not to break it. The lower part of the shoot is covered with soil. It is important that one or two buds are covered in this area. It can take up to two years for roots to form there so that the plant that growth can be separated from the mother plant. A small incision or a slight indentation in the bark, in the area that goes underground, is subserve to root formation.
- Carefully bend the lower shoot to the ground
- Fix the shoot
- Slightly groove the lower part at the bottom and cover with soil
- It is important that this area has one or more buds
- It takes one to two years for the roots to form
- Then cut off from the mother plant
The advantage of sowing shrub peonies is that the seedlings stand on their own roots and grow quite strongly right from the start. The downside is that the plants need around 5 years to flower for the first time. It can also happen that they do not have the same properties as the mother plant. So the flower color can vary. Wild species are best suited for sowing.
Tip: The seeds must be fresh. Seeds that are too old can no longer germinate.
It is best sown as soon as the pods or the so-called follicles can be opened easily. The seeds should still be very little immature, but never too much. If the seeds are too ripe or the time is too late, the dormancy has started. Then the seeds have to be stratified. For this, they are placed in a small plastic bag with a little damp sand and placed in the lower part refrigerator for 2 months.
During this time, tiny embryonic roots should have formed. The seeds come in a small pot and must now be kept warm, at around 20 ° C / 68 ° F. Always keep the substrate slightly damp, never too wet. The following spring, seedlings should have formed. It is best to keep them in containers for the first two years and not to take them outside in winter. Sometimes the seedlings need time until next spring.
- Alternatively, sow the mature seeds (around mid-September) outdoors
- Protection against mouse feeding is important. The little rodents love the seeds
- To promote germination and break germ inhibition, you can try the following method:
- Soak seeds in water for three days
- Freeze for a month
- Thaw for two days
- Freeze again for a week
Diseases and pests
On humus-rich soils, peonies often suffer from gray mold, and various leaf spot diseases can also occur. Occasionally, dwarfism caused by nematodes can occur when a newly divided peony has been planted in the same place again. This phenomenon is also known as soil fatigue. If your peony, which is about to bloom, is populated by numerous ants, there is no need to worry: the insects are only interested in the sugar juice, which the plants often produce in such large quantities that the buds really stick.
With increasing age, peonies gain frost resistance, so that adult specimens can easily survive up to – -20 °C / -4 °F. During the planting year and in the following two years, cover the planting site with coniferous twigs or leaves so that the young root balls do not freeze up.
If the weather forecast announce frost in the spring, cover the shoots and branches with a breathable fleece to protect the young buds. The branches of shrub peonies can break under a snow load. Before winter, tie the shoots together into a loose crotch and shake off the white hood if necessary.
Use in the garden
The common peony is one of the oldest garden plants and has been an integral part of the cottage and monastery gardens for centuries. Their double flower varieties with pink or dark red flowers are also very old. The Chinese peony (Paeonia lactiflora hybrids), which have also been known from Asia for several centuries, are ideal for sunny and partially shaded herbaceous beds. A classic combination often planted in the English cottage garden are perennial peonies, purple cranesbill (Geranium x magnificum) and lady’s mantle (Alchemilla mollis).
The fern leaf peony (Paeonia tenuifolia) comes from the Asian steppe and therefore feels very comfortable in full-sun, rather dry locations in the rock garden. It is best to plant shrub peonies in a single position in the front garden or in the bed. If you have enough space, you can also plant group plants. Shrub peonies can also be easily integrated into Japanese gardens. Suitable partners are, for example, the Japanese maple (Acer palmatum) and hostas (Hosta), as a background a bamboo grove is ideal.