New plant introductions – especially wild-collected – seldom prove to be horticultural game changers without intense breeding and selection. Parrotia subaequalis (Chinese parrotia) was introduced without great promotion or fanfare and is rare in cultivation, although it’s gaining traction.
It was previously described as Hamamelis subaequalis and Shaniodendron subaequalis until DNA work determined its relatedness to Parrotia. Roy Lancaster, the great English plant hunter, collector, and author, received cuttings from Mikinori Ogisu of Japan. The plants in my garden came from Ozzie Johnson in Atlanta, who introduced it in 2004 into the U.S. from the same source and shared it freely with friends. Peter Del Tredici, who observed and collected it in the wild, presented an excellent history of the species and the introduction to the Arnold Arboretum in Arnoldia 66(1): 2-9 (available online). Checking the Arnold’s online database, two seedlings and one cutting-derived plant from Peter’s work are now in the collections.
Four plants are scattered in the Dirr garden ranging from full sun to pronounced deep oak shade. All develop consistent fall color (maroon initially) followed by brilliant reds and purples, and the effect is long lasting. Emerging young leaves are fresh spring green and summer foliage is dusky, matte dark-green with fall color starting in early November in Athens, Ga. Dried leaves (marcescent) will persist into winter.
The species is cold (more so than P. persica), heat, and drought tolerant, as well as pest-free.
It’s a large shrub or small tree that grows 15 to 25 feet high and wide at maturity. Del Tredici reported a 30-foot high specimen in China. It will require pruning and staking to develop a single trunk. The largest specimen in the Dirr garden is 15 feet high and 10 feet wide.
The bark exfoliates on large trunks like P. persica. The largest one in the Dirr garden has a 6-inch diameter lower trunk and is exfoliating in jigsaw-shaped pieces, exposing the gray/green under bark.
It exhibits moderate growth rate in the garden.
P. subaequalis is well adapted to container culture. Container-grown plants in my shop grew 3 to 4 feet in a season. Pleasant Run Nursery in New Jersey offers container material, and Bold Spring Nursery in Georgia has beautiful field-grown trees. John Barbour of Bold Spring reported that after Hurricane Irma, P. persica ‘Vanessa’ required straightening and staking while P. subaequalis was not affected. He noted a much better root system on the latter.
Cuttings are easily rooted when firming in May and June. Apply 3,000 ppm KIBA, lightly fertilize after rooting (6 to 8 weeks), and watch as new growth ensues with no overwintering issues.
It’s hardy in USDA Hardiness Zones (4b) 5-8. In the Pacific Northwest it does not grow as fast, but develops excellent fall color. It survived the Polar Vortex in 2013-14 at Brotzman’s Nursery in Ohio where temperatures dropped between -25°F to -30°F. P. persica was severely injured, but only tip injury was observed on P. subaequalis.