Increasingly, gardeners are recognizing the historical and ecological appeal of native plants. Many growers want their landscapes to include what originally grew in their regions. One of my favorite natives for landscaping is the versatile Solomon's seal (Polygonatum). Equally at home in wildflower preserves, shade gardens, and perennial borders, Solomon's seal is easy to grow and valuable for its arching stems with smooth foliage. The flowers aren't showy, but in May (where I live), the small, greenish white, pendulous blossoms, followed several weeks later by dark blue berries, add to the subtle charm of this graceful plant. Though some species are native to Europe, Korea, and Japan, many are native to North America.
The tallest species, great Solomon's seal (P. biflorum commutatum, or alternately P. commutatum), appears surprisingly elegant in its natural woodland habitat, most midwestern and eastern states as far south as Louisiana to Georgia. Where leaf mold is deep and moisture is sufficient, stems will grow toward the light in 5-foot arches. In such locations, one plant may spread several feet across, so choose neighboring plants that will be in scale. It's hardy throughout USDA Hardiness Zones 3 through 9.
Other species are more modest in size but retain the same graceful form. Small Solomon's seal (P. biflorum) grows 20 to 30 inches tall. It naturally grows over a similar range as great Solomon's seal, and according to Miriam Patton, a naturalist in northwest Iowa, it is still common in deciduous woodlands throughout the state. Although small Solomon's seal is just as cold-hardy (through zone 3) as its larger cousin, it is somewhat less heat-tolerant, so it's only recommended through zone 8.
Two useful Asiatic species are P. humile and the variegated Solomon's seal, P. odoratum 'Variegatum' (alternately P. o. thunbergii 'Variegatum'). The former grows only 6 to 9 inches tall, making it a useful ground cover in shade. It is hardy from zones 4 through 9. Variegated Solomon's seal has creamy white leaf edges and dark maroon stems. This native of Japan is grown in gardens throughout this country.
Growing Solomon's Seal
Many garden centers offer plants, as do wildflower and perennial catalogs. Plants readily establish themselves, but patience is necessary to grow plants from seed.
At Garden in the Woods, the botanic garden of the New England Wild Flower Society in Framingham, Massachusetts, several species of Solomon's seal are propagated by seed and by division of rhizomes (enlarged underground stems that resemble roots). In the first season after planting seed, a small rhizome forms underground, but no growth is visible above the surface of the soil. The next year, a single leaf is visible, and in the third year, the typical curving stem appears with leaves.
Starting from seed. If you choose to try starting the plants from seed, Bill Cullina, propagator at Garden in the Woods, recommends picking a few berries when they have turned blue-black. Clean the pulp off the seeds, and plant them at once in a flat where they can be left for two years or more and watered as needed to keep them from drying out. Cullina keeps them in cold frames. Because Solomon's seal seeds should be planted soon after harvesting for best germination, he does not recommend buying seeds by mail.
Propagating the plants. You can also divide the branched rhizomes to propagate more plants. Very early in spring before the growing tips appear, dig and separate the rhizomes. Any piece that contains a growing point will grow if the piece is several inches long. Shorter ones are better left attached to a larger rhizome. The rhizomes store enough food and water that they often survive dry spells that cause some other plants to perish. Replant the rhizomes at a depth of 3 to 4 inches. Division may also be done later in the season. Don't worry if the leafy stem breaks off, but don't expect new growth before the next year.
Growing Solomon's seal in varied conditions. Though a moist, shady location is preferred for Solomon's seal, most kinds except P. humile are adaptable enough to be grown successfully in hot, dry climates, if gardeners are attuned to the plants' needs. In high-desert areas of Idaho and Utah, where August brings strong, dry winds and temperatures over 100°F for up to two weeks, creating a garden of woodland plants requires the use of soaker hoses, fences for shade and windbreak, and a mulch that will not blow away.
Garnette Monnie, owner of Edwards Greenhouse in Boise, Idaho, says, "Even more than heat, the alkaline soil is a problem for some perennials." She recommends amending the soil with peat moss or with finely ground pine bark. Anju Lucas, who grows perennials for Edwards, adds compost containing horse and goat manures to Solomon's seal in her own garden. Ferns succumb to the hot wind, but Solomon's seal survives. She confirms: "It's very adaptable." When soil is alkaline (pH higher than 7.5), other gardeners use shredded oak leaves mixed with compost, grow the plants in raised beds, and add iron sulfate for acidity.
Near Portland, Oregon, Solomon's seal grows well in soil with a pH of 5.0 to 5.9. Robyn Duback, owner of Robyn's Nest Nursery in Vancouver, Washington, suggests letting colonies of the taller kinds build up as a background for other shade perennials. However, low-growing P. humile is more susceptible to slug and snail damage than are other Solomon's seals, most of which are not injured by slugs. Duback prefers not to plant Solomon's seal in creekside gardens where slugs may abound.
Companion Plants
Goldie's wood fern (Dryopteris goldiana, zones 3 through 8) and ostrich fern (Matteuccia struthiopteris, zones 3 through 7) are large, sturdy ferns whose curving fronds complement great Solomon's seal. Geranium maculatum, a hardy wild geranium with mauve-pink flowers, is native to eastern and midwestern woods, but it is easy to grow in any moist shade garden where Solomon's seal thrives. If you aren't focusing strictly on native American plants, also consider G. sylvaticum 'Mayflower', a variety from England, with flowers of violet-blue around white centers.
Leaves of variegated Solomon's seal are most distinct in front of a dark background. For a trouble-free background shrub, try Fothergilla 'Mt. Airy' (zones 4 through 8) with dark blue-green leaves and fuzzy, creamy white flower clusters. In 1994, this plant received a gold medal from the Georgia Plant Selections Committee for its appealing features and adaptability to various soils and climates.
White-flowered plants can create an engaging composition with variegated Solomon's seal. Choices to try include Astilbe arendsii 'White Gloria', white impatiens, Phlox stolonifera 'Bruce's White', and Pulmonaria officinalis 'Sissinghurst White'.
Ferns' airy compound leaves make an interesting contrast with the smooth leaves of Solomon's seal. Plant it with groups of low-growing ferns (8 to 12 inches) like the fringed lady fern (Athyrium filix-femina 'Fancy Fronds') and Japanese painted fern (A. niponicum 'Pictum'), which are hardy in zones 4 through 8. Slightly taller maidenhair ferns (Adiantum aleuticum and A. pedatum), reaching about 18 inches, are also good companions.
Photography by Ohio Department of Natural Resources
