You can’t miss the peonies that bloom in May! It is the largest and most showy of the spring flowers here in Ohio. It is a perennial plant that blooms every year.
Peonies have three different growth habits. Herbaceous peony (Paeonia lactiflora) is the most common. It dies each fall and begins to sprout new growth in the spring, resulting in a bush that can reach 3 to 4 feet tall. The stem usually produces a single flower.
The tree peony (Paeonia suffruticosa) and related hybrids, is not actually a tree but rather a deciduous shrub. It is a slow growing plant with a single woody stem that can be 4 to 6 feet tall. Although the leaves fall in the fall, do not cut the stem if you want to see it bloom the following spring.
The third type of growth habit is the intersectional peony. It is a bushy type but smaller than the herbaceous. Like herbaceous plants, it dies on the ground in the fall. This peony was developed by crossing the tree peony with the herbaceous peony and the result is also called Itoh peony or Itoh hybrid. The outstanding flowering feature of this peony is that it comes in a variety of colors not available in the herbaceous or tree peony.
The American Peony Society recognizes eight color classes: white or yellow, bluish, light pink, medium pink, dark pink, light red, medium red and dark red.
Peonies have large outer petals that surround pollen-containing stamens. There are six peony flower shapes that depend on the “transformation” of the stamens ranging from very prominent and visible to non-existent.
‘Double Form’ has the heaviest flowers of any form. Another showy form is called the “Bomb”, which opens small and gradually enlarges as it matures. The stamens are not visible.
Single, Japanese and Anemone have a single outer layer of petals, but the stamens in the center follow a pattern of transformation and range from yellow to the same color as the outer petals.
The sixth flower form is the “semi-double” which has a significant number of outer petals, but fewer smaller inner petals. The central ring of yellow stamens is clearly visible.
Gardeners should consider site selection before planting or dividing peonies. Well-drained soil in an area that receives at least six hours of full sun is most desirable.
Planting or dividing and replanting should be done in the fall so that the root system can become established before top growth occurs. Mulch only the first year, then remove excess soil in the spring.
Potted plants sold in garden centers and nurseries should have well-established roots and can be planted in the spring.
Encourage your peonies to grow and bloom by adding nitrogen fertilizer to the soil in the spring and halfway through the growing season. Be sure to follow the instructions on the packaging.
As the peony continues to grow in the spring, it’s a good idea to use a garden fence to support the plant. Nothing is more disheartening than seeing all the beautiful flowers and foliage flattened on the ground after a spring storm.
Insects and diseases
Some people worry that their peonies are sick because they see ants on the stems and flowers. Entomologists explain that the ants sip nectar and do not harm the peony at all.
When you cut the peony to bring it indoors for a vase of flowers, be sure to shake off the ants. The peony vase will be a beautiful addition to your table.
Although peonies are rarely bothered by disease or insects, the gardener should watch out for scale insects and botrytis.
The scale can be seen on the stems and the base of the leaves in summer. It overwinters on the ground part of the stems during the winter. Remove plant material in late fall and apply an appropriate insecticide in late May of the following year.
Botrytis is a parasitic soil fungus. In the fall, cut the plant back and burn all the leaves and stems. Spray with Bordeaux mixture from early spring until August. A top dressing of sand around the crown of the plant often helps control the blight.
Christine Michael is Master Gardener at the Sandusky/Ottawa County Extension Offices.