May 6th, 2015 by Soest Gardener, Riz Reyes
The peony has been a staple in gardens for hundreds of years and the UW Botanic Gardens has a wonderful representation of the genus this month at both the Washington Park Arboretum (WPA) and the Center for Urban Horticulture (CUH).
This month we are highlighting a spectacular peony that’s currently in bloom in the Pacific Connections Entry Gateway. Visitors stopped in their tracks by the large, dinner plate-sized blooms which emit a wonderful scent. This is a pink form of the typically white flowered P. rockii. Found in Northwest China in Gansu Province. This species is characterized by a deep purple pattern in the center of each petal.
This type of peony is referred to as a “Tree Peony” by most gardeners. Although it’s not technically a tree, it is a woody shrub that does not die back and should not be cut down in the autumn like the more common bush peonies many people know. But like the bush form, it takes a few years before the plant is established and starts blooming well.
Both types are generally planted in the fall, but potted plants can be purchased and planted just about any time of year (except when the ground is frozen).
Genus species: Paeonia suffruticosa subsp. rockii
Common Name: Rock’s Peony, Joseph Rock Peony, Ziban Mudan
Location: WPA – Pacific Connections – China Entry Garden
Origin: NW China, Gansu Province
Height and Spread: 5-7′ height x 6′ width spread on mature, undisturbed plantings
Bloom/Fruit Time: April-May
May 6th, 2014 by Soest Gardener, Riz Reyes
Joseph Rock’s Peony has been prized by gardeners and avid collectors for decades. Botanist and plant explorer Joseph Rock earned the honor of having this exquisite flower named after him.
Peonies are divided into two basic types; the bush or herbaceous peony and the so-called tree peony. With similar flowers, the main difference between the two are their bloom times and their growth habit. Herbaceous peonies die back down to the ground each winter and bloom later in the season (May-June) whereas the tree peony, which isn’t really a tree, is more like a shrub with stems and branches that do not die back to the ground and flower mostly in May. Paeonia rockii is a tree peony.
Tree peonies are long-lived shrubs with exquisite flowers, but they take careful placement and a lot of patience until they’re well established.
They are best planted in the autumn so they are able to start forming new roots over the winter and it’s critical that they are planted in a location with full/part sun, well drained soil, good air circulation, and protected from strong winds that could damage the brittle branches. They can take several years to get established to consistently bloom each year and they also resent being transplanted.
Common Name: Joseph Rock’s Tree Peony
Location: Pacific Connections – China Entry
Origin: Gansu, China
Height and Spread: 6-8′ tall and about 5-7′ wide
Bloom/Fruit Time: Early-Mid May
A few selections of P. rockii can also be found growing at the Seattle Chinese Garden.