Pacific Plant Promotions: Polygonatum prattii

By: Richie Steffen

Richie Steffen is curator of horticulture for the Elisabeth C Miller Botanical Garden in Seattle, where he manages the rare…

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Flowers and spring foliage of Polygonatum prattii. Author’s photographs

Flowers and spring foliage of Polygonatum prattii. Author’s photographs

The Elisabeth C Miller Botanical Garden is the first in the Northwest to join the Pacific Plant Promotions program of offering exceptional plants to readers of Pacific Horticulture.

Virtually no woodland garden is complete without the presence of at least one species of Polygonatum, generally known by its common name, Solomon’s seal. About sixty species of Polygonatum are known to science. They occur on every continent in the Northern Hemisphere, with the majority native to China and Japan. China can lay claim to thirty-nine species growing within its vast borders; twenty of the species are endemic to (only found in) China.

I have had the pleasure of growing many Asian species, including one of the endemics, Polygonatum prattii, at the Elisabeth C Miller Botanical Garden in Seattle. Native to forests, thickets, and grassy slopes in mountainous areas of western Sichuan and northwestern Yunnan provinces, P. prattii occurs at an elevation of 8,200 to 10,800 feet. The Miller Garden received plants from Diana Reeck, owner of Collector’s Nursery in Battleground, Washington. Her stock originated from seed collected in Yunnan. We are proud to be able to share this choice perennial with the readers of Pacific Horticulture through the Pacific Plant Promotions program.

We typically think of Solomon’s seals as herbaceous plants having tall, slender, gracefully arching stems with rows of delicate white, bell-shaped flowers dangling beneath the fresh spring green foliage, but this genus is actually quite varied. Polygonatum prattii is a low-growing Solomon’s seal ranging from four to eight inches tall; it spreads slowly to create a colony of miniature arching stems. The mat green leaves are about one to one and one-half inches long and oval in shape, arranged in an alternating pattern along the stem and often terminating in a characteristic whorl of three. Soon after growth starts in spring, tiny, pinkish purple, pendulous flowers appear, delicately attached at the leaf axils. The tubular, bell-shaped flowers are tipped in delightfully upturned lobes; although a tiny feature, the effect adds to the overall charm of the flowers. In late summer, berries begin to mature, first becoming green with purple brown blotches, ultimately progressing to brilliant crimson red, which contrasts nicely with the golden fall foliage.

Our plant took about two years to settle in before starting to spread. The smaller size of this species makes it suitable for pot culture, and it shows well in troughs or woodland containers. The Miller Garden’s specimen was grown for six years in a large shallow bulb pot (fifteen inches wide by six inches deep) and sprouted robustly through a collection of native mosses covering the soil in the container. The best summer foliage color appeared in a situation offering morning sun and afternoon shade, protecting plants from the hottest temperatures of the day. Published reports note that it is a more sun tolerant species when compared to other species of Polygonatum, and I would agree, with some reservations. In full sun, our plants, even in the cool Seattle climate, would show a yellowing of the leaves from the intense rays. The heat tolerance is virtually untested with this plant, although I would expect it to perform well in USDA hardiness zones 6-9 with adequate summer watering. In our experience, growth has been best in a rich, well-drained, acidic soil with plenty of organic matter. We have recently planted a division in heavy clay; it has grown well so far, but it will take another two or three years to develop its full potential.

As part of the Pacific Plant Promotions program, the Elisabeth C Miller Botanical Garden will be offering plants of Polygonatum prattii to readers of Pacific Horticulture. Dormant, three-year-old plants in two-inch pots will be shipped in November, 2007. To order one, see the Pacific Plant Promotions reservation card (opposite page 57) for details.

The staff of the Miller Garden have generously offered to donate proceeds from these sales to Pacific Horticulture.

Ripened fruits and autumn foliage of Polygonatum prattii

Ripened fruits and autumn foliage of Polygonatum prattii

Elisabeth C Miller

The Elisabeth Carey Miller Botanical Garden is the former residence of its namesake, who gardened on the sloping, west-facing site north of Seattle from 1948 until her death in 1994. Mrs Miller initially approached horticulture with a painterly eye, having been trained in the fine arts. Gradually, she developed a passion for plants, particularly tough landscape plants, unusual plants, and those from China, where she had traveled. She created a framework of native trees and shrubs to shelter her exotic treasures. Mrs Miller also liked to exchange plants with fellow gardeners. Between 1966 and 1989, my friend Alleyne Cook created the Ed and Mary Grieg Rhododendron Garden at Stanley Park in Vancouver, BC. Ed met Mrs Miller on about six occasions. Responding to her request for tender rhododendrons in the Subsection Maddenii, he propagated a truckload of plants and brought them down to Seattle. Waiting for him was an equally large truckload with many types of groundcovers, a Lithocarpus, and an Enkianthus to take back to Stanley Park.

Carolyn Jones,
director, Miller Garden