Peonies are the stars of any May bed, taking the limelight with their opulent blooms. Here, you can find everything you need to know about planting and caring for peonies.
The peony genus (Paeonia) comprises herbaceous perennials as well as sub-shrubs and shrubs. Chinese peonies and Moutan peonies, referred to as tree peonies, are comparable in their significance to gardening culture. Previously part of the buttercup family (Ranunculaceae), the genus now forms its own plant family, known simply as peonies (Paeoniaceae). There are 32 species worldwide, all native to Europe and Asia with the exception of two species native to the West Coast of America. Peonies have long been grown as garden plants. The most significant European species is the common peony (Paeonia officinalis) native to mountainous regions of southern Europe, while tree peonies (Paeonia Suffruticosa hybrids) and Chinese peonies (Paeonia Lactiflora hybrids) have defined gardening culture in China for 2,000 years. The original species come from the mountain forests here, as well as steppe regions of temperate and subtropical climate zones.
The plants were named after the Greek god Paeon. According to legend, he used the peony to heal the wounds of god Pluto, injured by Heracles in the battle of Pylos. The common peony used to be a very significant healing plant. All parts of the plant are slightly toxic but were used to treat gout among other ailments. As its medical efficacy has not been proven, it is no longer used in medicine.
Chinese peonies grow in upright clumps up to no higher than knee height depending on the species and variety. They form tuberous storage roots with overwintering buds arranged densely under the surface.
Moutan peonies form strikingly thick, upright shrubs with little branching. The largest varieties mostly come from the Rockii hybrid group. They can grow over 6.5 feet tall and almost twice as wide over time. The plants grow very slowly and have strikingly large buds that start growing very early on in the year.
Intersectional hybrids, also known as Itoh hybrids, form a very new group of peonies. These are crosses between Chinese and Moutan peonies. They have herbaceous shoots but grow more voraciously than Lactiflora hybrids and have larger flowers.
Location and soil
Peonies, unlike most other garden plants, prefer mineral, rather humus-poor soils. They like to grow in somewhat heavier, loamy and evenly moist, well-drained substrates. Peonies are quite adaptable, however, as long as the soil is not too dry. The site should be full sun to partial shade. Strong root pressure from large woody plants is not tolerated by most species.
The best time for planting peonies is in the fall. When planting peonies, observe the following basic rule: plant perennial peonies shallow and shrub peonies deep. The reason: perennial peonies often form only leaves and no flowers if they are too deep in the soil. Shrub peonies are grafted onto root pieces of perennial peonies. Therefore, they must be planted deep enough in the ground so that the grafting point of the plants is about three finger widths below the soil. It is important that the scion forms its own roots, as it will not be able to form a permanent bond with the perennial peony, and so sooner or later it will start to take care of itself. It is also important to lean humus-rich soil with plenty of sand or clay granules before planting peonies in the garden. Also, do not choose a too sheltered, warm location for shrub peonies. Otherwise, the bushes will sprout quite early and then will be at risk of late frost.
Tips for planting
Perennial peonies are long-lived and do not overage. Therefore, the plants do not need to be rejuvenated by division. If you just let them grow, lactiflora peonies will become more magnificent every year. However, if you want to repot a perennial peony, it is very important that you divide the perennial in the process. Undivided plants grow poorly in the new location and sometimes take care of themselves in the garden for years. During the blooming season, the heads of perennial peonies lean heavily under the weight of the large flowers. Then a support in the form of a perennial holder may be advisable. After flowering in the fall, the perennial peonies will move in. Old stems of the plants can be cut off in late winter.
Pruning peonies is usually not necessary. However, well-rooted shrub peonies can tolerate more severe pruning down to the old wood in an emergency. However, even without regular pruning, the plants form a balanced crown with many flowers. In addition, shrub peonies are very long-lived in the garden. Specimens over 100 years old are known from China.
If you want to fertilize your peonies, the fertilizer should not be too rich in nitrogen. The plants then often become susceptible to fungal diseases. A potassium and phosphate fertilizer of organic origin (horn shavings, bone meal, mature manure, not compost!) applied in early spring promotes the vitality and budding of the plants for the coming year.
Tipp: Pfingstrosen produzieren einen süßen Zuckersaft. Dieser kann die Knospen der Pflanzen stark verkleben. Dann öffnen sie sich nicht mehr. Waschen Sie den Sirup vorsichtig mit warmem Wasser von den Blütenknospen ab.
Overwintering and winter protection
Both perennial and shrub peonies are fully hardy. Perennial peonies, as is common with perennials, retreat into the ground over the cold season and overwinter in the form of tubers. Shrub peonies are prone to breakage during snowy winters. As a precaution, therefore, you should loosely tie the somewhat brittle, fragile shoots of the plants together with rope in the fall. This will allow them to support each other.
The common peony is one of the oldest garden plants in Europe, and has been a firm fixture of farm and monastery gardens for centuries. Even double varieties in pink or dark red are very old. Also around for a few centuries, Lactiflora hybrids exported from Aisia are ideal for sunny to partially shaded perennial beds. A classic combination often seen in English cottage gardens comprises purple cranesbill (Geranium x magnificum) and lady’s mantle (Alchemilla mollis).
The fern leaf peony (Paeonia tenuifolia) comes from the Asiatic steppe, so will feel right at home in rather dry locations with full sun, such as in a rockery. Moutan peonies are best off planted individually in a front yard or flower bed. If you have enough space, you could also plant groups. Particularly imposing Moutan peonies can be seen at the Arboretum Ellerhoop in Schleswig-Holstein, Germany. Here, the plants are impactfully arranged in an artificial landscape of hills. Moutan peonies are also great for integrating into Japanese gardens. Suitable partners include the Japanese maple (Acer palmatum) and hostas with a bamboo grove to provide a backdrop.
Important species and varieties
The diversity of varieties of peonies is immense. Intensive breeding has resulted in hundreds of varieties of Paeonia for planting in the garden. Therefore, we provide here only a small insight into the species and varieties of peonies:
- Paeonia officinalis: The common peony is native to Europe and belongs to the original forms of peonies. It is characterized by its robustness and is the plant with the most pollen grains per flower - so it is a real bee magnet.
- Paeonia lactiflora 'Sarah Bernhardt': This historical peony reaches a height of almost one meter. Its main flowering season is in June. The strongly fragrant white flowers grow to about 20 centimeters tall.
- Paeonia lactiflora 'Bowl of Beauty' is a visually appealing Japanese peony with double flowers without fragrance. The outer leaves are fuchsia pink, while the filler leaves are light yellow. The peony reaches a height of growth of just under 60 centimeters.
- Paeonia x hybrida 'Paula Fay': Lactiflora hybrid with neon pink flower that opens in May. Height of growth about 50 centimeters. The semi-double flowers are not fragrant.
- Paeonia tenuifolia: The "net leaf peony" is characterized by its finely slit foliage above which the simple, dark red flowers seem to float. Common varieties of the perennial peony are 'Plena' or 'Rubra Plena'.
- Paeonia rockii: The wild species of shrub peony grows up to two meters high. It displays lightly fragrant white flowers, which may be double or single. The flowering time is in May.
- Paeonia x suffruticosa 'Teni': the color of the almost fully double flowers, which open in June, is "cherry blossom pink". At one meter in height of growth, 'Teni' - translated as "fairy" - remains rather small.
- Paeonia x suffruticosa 'Higurashi': A Japanese peony hybrid with 16-centimeter, old-pink flowers. Rather small at 1.3 meters final height. This variety of peony is not fragrant.
- Paeonia x suffruticosa 'High Noon': A 1.50-foot-tall shrub peony hybrid with lemon yellow flowers and red basal blotch. The semi-double flowers open in June. They are rather small at about ten centimeters and without fragrance.
- Paeonia x itoh 'Scarlet Heaven': 80 centimeter tall, bushy peony cultivar with single red flowers.
Paeonia x itoh 'Yellow Crown': Semi-double, yellow flower with red basal patch. Flowers grow up to 18 centimeters tall on stems 50 centimeters tall.
- Paeonia x itoh 'Old Rose Dandy': This American hybrid from Laning shows several flower colors between beige and purple, yellowish in bloom. Its 15 centimeter single flowers are semi-double. The plant grows to about 80 centimeters tall.
Paeonia x itoh 'Lollipop': With its brightly colored flower of yellow with purple, this modern hybrid variety lives up to its name. Its showy semi-double flowers grow up to 20 centimeters tall. The height of growth is up to 90 centimeters.
Chinese peonies can be propagated through division. Various Moutan peonies are grafted onto Chinese rootstock in spring before being potted on. This type of grafting usually involves grafting the scion into a cleft, ensuring the survival of the scion until it has formed its own roots.
Diseases and Pests
In humus-rich soil, peonies often suffer from gray mold, and various leaf spot diseases may take hold. Sometimes, nematodes can cause stunted growth if a freshly divided peony is replanted in the same location. This phenomenon is also known as soil fatigue. If you see lots of ants on your peonies just before they flower, there’s no reason to worry: these insects are just interested in the sugary liquid that the plants often produce in such large quantities that the buds become stuck.
Frequently Asked Questions
When can peonies be planted?
Peonies are best planted in September. This lets the peonies root before the first frost.
What kind of soil is suitable for peonies?
A mineral, low-humus, loamy soil is ideal for peonies.
What can be used to fertilize peonies?
In spring, peonies should be fed with an organic fertilizer containing potassium and phosphate.
From when do peonies bloom?
Peonies tend to start blooming between late April and early May.
When can peonies be moved?
Peonies should ideally be moved in August to September.
Why might a peony fail to flower?
A lack of flowers may have several causes, such as the wrong choice of location or incorrect care. One of the main causes is usually incorrect planting. If a Chinese peony is planted too deep, it often only grows leaves.