Peonies - The Tree Peony

Peonies Part 4 - The Tree Peony

While the herbaceous type peonies are very common, tree peonies are less so. They are different from the herbaceous and ITOH peonies in many ways - a bit harder to grow and propagate, less available and more expensive, come in a wider variety of colors, have different growth habits, require different fertilization and may be more drought tolerant.

While herbaceous peonies and ITOH’s grow to a height of 2-4’, tree peonies can reach a height of 4-6’. There is nothing more spectacular than a mature tree peony in full exotic bloom, and for this reason it’s worth adding to your landscape. Patience is required however. Where an herbaceous or ITOH peony might take a season to establish, a tree peony is slower growing and may take 2 or 3 seasons to develop, especially a grafted variety. Tree peonies grow for many years and if cared for, will bloom annually.

Tree peonies are shrub-like, with perennial woody stems and once established, will produce many flowers. The centers of the blooms are yellow, pink, or red with the petals mottled at the throat, and petals can be yellow, pink, white, rose, crimson, scarlet, purple or deep purple -- every color except blue. Contrary to the herbaceous and ITOH peonies, whose stems die down in the fall when freezing weather arrives, the woody stems of the tree peony remain alive all winter and it only loses its leaves in winter. This feature allows it to provide structure in a winter landscape. Dead leaves should be removed and disposed of once they fall off in winter. Leaves left on the ground can harbor disease spores and cause infection in the Spring.

Careful consideration should be given in selecting the location for planting a Tree Peony. Like other peonies it needs good drainage and plenty of sunlight - 6-8 hours at least with morning sun being best -- as blooms will last longer if sunlight is filtered in the heat of the day. They also need to be sheltered from strong winds. If you’re planting a bare root tree peony, it should be planted in the fall. If you’re planting a potted tree peony, it can be planted in the fall, winter or spring.

Tree peonies are grown either from seed or grafts, with the more desirable way for the home gardener being grafted plants. Tree peony tubers should be planted so that four or five inches of soil covers the graft. The graft can be determined by the ridging on the stem and the different texture of the bark. By planting deep, the grafted section will establish its own roots in the soil. Add 2-3 handfuls of dolomite lime to your planting hole along with a handful of bone meal and another of fertilizer. Water it in after planting.

Water when the weather is exceptionally dry, especially during bloom. Drooping foliage will tell you the tree is stressed and in need of water. If the leaves are browning and crisp on the edges, you are not watering it enough. After flowering, over the summer months, the roots of a tree peony will shut down. This makes them very hardy to dry conditions since the roots are not active.

Tree Peonies, unlike all other plants, do all their root feeding and storage in the coldest months of the year from mid-Fall, before leaf fall, to the end of Winter, when pink roots appear. During this time, they can be fed N-P-K fertilizer, preferably low in N but high in P and K, in addition to dolomitic lime (high in calcium and magnesium) and iron in the form of Ferrous Sulphate, which is readily available. A small handful of each, spread around the base of the plant once a month for the four coldest months is sufficient. If the plant is well established in its location for 3-5 years, more can be applied. The rains we have during this time of year will help incorporate these amendments into the soil.

Peony pruning really only comes into play with tree peonies, which have woody stems. The most common pruning you’ll tackle with tree peonies is removing winter-damaged wood in late spring. This occurs most often in colder regions where harsh winters can kill some of the stems. Wait to prune until late spring, when growth has clearly resumed from some of the buds. Place pruning cuts just above an outward-facing bud and cut stems at an angle.

I hope you’ve enjoyed this series of blogs that are all about Peonies. Keep following my blogs for more growing advice and tips for your Zone 8 garden.

Until then - Happy Gardening!