Tree peony (Paeonia suffruticosa) plants are, in fact, woody perennial shrubs. They are not to be confused with the herbaceous garden peony (Paeonia lactiflora). Producing huge, colorful flowers and interesting foliage that dies in the winter, it has bare stems until spring. The Chinese and Japanese tree peonies (Paeonia suffruticosa) are all cold-hardy, easy to care for, and long-lived. They grow in most regions of the U.S. where it gets chilly in the winter.
Tree peonies typically grow to be 4' – 5' tall and spread on upright, gray-green shoots about as wide as they are tall. Those that grow in warmer climates may eventually reach 6' in height. Bearing leaves at the branch ends, they usually round out to be a large shrub. The Chinese types of tree peonies tend to be bushier than their Japanese cousins and are more likely to spread out underground.
Tree peony flowers bloom in the spring about 10 weeks after their leaves appear. Those of the Japanese variety appear somewhat earlier than the Chinese. There are single, semi-double, or double-flowered kinds of tree peonies, and many have a pleasant fragrance of pine, rose, or citrus. Sometimes heavy, nodding blooms need to be individually staked.
Tree peony foliage is handsome in its own right. Leaves are usually reddish or purplish when they unfurl in the spring, turning gray-green for the season. Sometimes they redden in the fall just before they drop. Up to 8" or 10" wide, they're deeply cut into large, pointed lobes.
Frequently Asked Questions
Q: When can blooms be expected?
A: In some cases, you may get flowers the first season in mid-summer (if the temperatures don't turn into extreme heat too fast). If you do get them, however, they won't compare to the second season's impressive showing.
Q: Are ants on the blossoms a sign of pests?
A: No. Ants feed on the sweet sugary nectar of the flowers. Peonies are almost pest-free.
Q: Can tree peonies be divided or moved?
A: No. They shouldn't be bothered unless absolutely necessary. If they haven't flowered for a while or don't flower well, you can dig around them and re-plant less shallow. Do this in the spring. If you do any of the above, they often miss a season of flowering. Since they live for decades, a little medicine is well worthwhile.
Q: Does the planting depth make a big difference?
A: Yes. If planted too deeply, they'll grow but won't flower well. For best results, plant vertically and dig a hole two times the width of the roots. (It must be deep enough to accommodate the roots plus 1" – 2" of stem.) Pack in well. Water thoroughly and ensure water reaches the entire root zone.
Q: Do they need to be cut back?
A: No, they're woody shrub-like peonies. New growth will fall away on its own and harden up on the parts left on plant.