Solomon's seal (Polygonatum) is a genus of elegant perennial plants native to woodland areas of several continents, including North America. Although the small, tubular flowers, which come in white, green, or pink, are charming, it's the slender arching stems and long, lance-shaped leaves that make Solomon's seal such a favorite in shade gardens and woodland settings. Small blackish berries remain after the flowers fade, often enjoyed by birds. Once established, Solomon’s seal slowly spreads and creates a blanket of foliage that turns a golden yellow in autumn. Most of Solomon's seal plants grow one to two feet tall, but there is a giant Solomon's seal (Polygonatum biflorum var. commutatum) that reaches around five feet tall or higher and really makes a statement in the garden.
These plants grow at a moderate pace and can take a few years to reach blooming maturity when started from seed. They are best planted in the spring or fall from potted nursery plants or root divisions. Be aware that Solomon's seal contains cardiac glycosid chemicals, which are mildly toxic to humans and animals. The berries contain the highest concentration of these toxins.
|Common Name||Solomon's seal|
|Botanical Name||Polygonatum spp.|
|Plant Type||Herbaceous, perennial|
|Mature Size||6 in.–7 ft. tall, 1–4 ft. wide|
|Sun Exposure||Partial, shade|
|Soil Type||Moist, well-draining|
|Soil pH||Acidic, neutral|
|Flower Color||White, green, pink|
|Hardiness Zones||3–9 (USDA)|
|Native Area||North America|
|Toxicity||Toxic to people., toxic to pets|
Solomon's Seal Care
Solomon's seal plants are native to woodland areas, so they prefer to grow in a spot with some shade and dampness. Gardeners usually start their plants with transplants or rhizomes (underground stems that produce new plant shoots).
Solomon’s seal does not require deadheading (removing spent blooms). The flowers are small and will drop off naturally. Plus, the foliage remains attractive for the entire growing season (spring to fall), so the plant is virtually maintenance-free with no need for pruning. The stems even disconnect from the rhizomes on their own after frost in the fall.
Solomon's seal plants are naturally found growing under large shade trees in dappled light. So an ideal planting site in your garden should have partial to full shade. They can tolerate more sun when grown in cooler climates.
These plants like cool soil that’s rich in organic matter and has good drainage. A slightly acidic to neutral soil pH (5.0 to 7.0) is ideal. To increase the richness of your soil, it can be helpful to add a layer of compost around your Solomon’s seal each year. Allowing leaf litter to decompose around the plants creates a rich, humusy environment the plants enjoy.
Solomon's seal plants prefer soil that remains evenly moist but not soggy. Young plants should be watered regularly to maintain consistent moisture in the soil. Established plants still prefer to be in soil that is damp to the touch, though they can tolerate short periods of drought if necessary.
Temperature and Humidity
The various species of Solomon’s seal are generally hardy in USDA hardiness zones 3 to 9, though with some variation between species. While they prefer cool and shady environments with some humidity, Solomon's seal can successfully grow in hot and dry climates with some help. Make sure the plants have ample soil moisture and shade, as well as protection from strong, hot winds. A layer of mulch around the plants can help to keep their roots cool and moist. In the fall, frost will cause the plants to die back to the roots for the winter.
Because this plant likes to grow in plenty of organic matter, mix some compost into the soil of your garden site when first planting Solomon's seal to give it a good start. Then, continue to add an organic fertilizer or compost each year at the start of the growing season to give your plant a boost, especially if you don't have naturally fertile soil. No other artificial feeding is needed.
Types of Solomon's Seal
There are more than 60 species within the Polygonatum genus, though a relatively small number of these are commonly cultivated for garden use. The species have very similar growing requirements but can range in size, coloring, and other factors. Some popular varieties for garden applications include:
- P. odoratum var. pluriflorum 'Variegatum' reaches around one to three feet tall, and its leaves have white edges. The white flowers have a sweet fragrance reminiscent of lilies. This is one of the most popular of all Solomon's seals, and the one that is often recommended as the best introduction for gardeners. It is native to Europe and Asia and hardy in zones 3 to 8. Other common cultivars of this species include: ‘Goldilocks’, with whitish streaking through the leaves; ‘Angel Wing’, which has wide white leaf margins; Byakko’, with white splotches near the leaf bases; ‘Double Stuff’, which has extra-wide margins; ‘Koryu’, with green leaves with a raised center ridge; and ‘Spiral Staircase’, with larger leaves and slightly twisted stems.
- P. biflorum, also known as smooth Solomon's seal, is a North American native that grows roughly one to three feet tall. Its leaves are smooth on both sides, and the plant features white-green flowers. It is a good choice for small gardens. It is hardy in zones 3 to 9. One variation, P. biflorum var. commutatum (giant Solomon's seal), grows 6 1/2 feet tall, and tends to colonize in large groups.
- P. humile is dwarf species that grows just six to nine inches tall. It has relatively large flowers for its size, but it is only hardy in zones 6 to 9. It is native to China and Japan.
- Polygonatum 'Prince Charming' grows to only about a foot tall, but it spreads to around two to three feet wide. 'Prince Charming' plants tend to bloom at a younger age than many other Solomon's seal types and feature greenish-white flowers. It is thought to be a natural hybrid between P. biflorum and P. humile.
- P. multiflorum is a European species. ‘Variegatum’ is an excellent short selection (under two feet) with cream and green leaves on reddish stalks. It is hardy in zones 4 to 8.
- P. odoratum thunbergi , also known as fragrant Solomon's seal or Japanese Solomon’s-seal, is native to Japan. The plants grow 18 to 36 inches tall with reddish stems and have fragrant white flowers. It is hardy in zones 4 to 8. There are several cultivars of this species including 'Fireworks', 'Flora Plenum', 'Lemon Seoul', and 'Variegatum'.
Propagating Solomon's Seal
Like most plants that grow from spreading rhizomatous roots, Solomon's seal is easy to propagate from rhizome divisions. Dig up the parent plant, simply slice off portions along the rhizome, and replant them. Here's how:
- In spring, as new growth emerges, or in fall, dig up the parent plant. Use a sharp shovel or knife to carefully slice off sections of the plant's rhizome.
- Immediately replant this divisions horizontally a few inches deep in a garden location that has been prepared by amending with compost.
- Water thoroughly upon planting, and then regularly until the new division is well established.
Division is not necessary for the health of the plant, but only if you want to propagate new plants or control the rather slow spread of a clump.
Growing Solomon's Seal From Seed
While it is entirely possible to propagate the various species of Solomon's seal from seeds collected from the dried flower heads, it is not an easy process and it will take seedlings several years to achieve flowering maturity. Thus, it is rarely done except for species where live plants are unavailable and purchasing seeds is the only option.
Solomon's seal seeds are generally given a month-long cold stratification period in the refrigerator, then sown in seed trays, where they are kept warm and moist until they sprout—which can take several months. Once the seedlings have been nursed to a size where several sets of true leaves are present, they can be transplanted outdoors. After two or three more years, the plants will begin flowering.
These very hardy woodland perennials need no preparation for the winter or protection from the cold. In fact, it is best to let garden debris simply remain in place and decompose to offer nutrition to the plants.
Common Pests & Plant Diseases
Healthy Solomon's seal plants growing in optimal conditions have few problems with pests and diseases. If the weather is extremely damp, you might see signs of a fungal disease, which can appear as discoloration on the foliage. Ensuring good air circulation around the plant can help to prevent and combat such issues.
Solomon's seal is also prone to foliar nematodes, which usually reveal themselves as brownish streaks on the leaves. The same nematodes may affect hostas and ferns. The only remedy is to promptly remove affected plant parts. Slugs and snails can also become a problem, so watch out for holes in the leaves and stems.
How to Get Solomon's Seal to Bloom
These plants are normally grown for their foliage. But, if lack of flowers is troubling to you, look to cultural problems, such as too much sun or the presence of pathogens such as foliar nematodes or fungal diseases.
Simple patience sometimes corrects a flowering problem. Recently divided or newly propagated plants can take quite some time before they become established and mature enough to bloom.
Common Problems With Solomon's Seal
Largely trouble free, Solomon's seal is regarded as one of the easiest of all woodland perennials to grow. But in extreme heat or conditions that are too sunny, the leaves can turn brown and crispy. Make sure to water amply during the hot summer months, especially if the plants must tolerate some afternoon sun.
How did this plant get the name "Solomon's Seal"?
If you inspect the rhizomes, you will see rounded scars where the previous year's stems were attached. These scars are thought to resemble the two inverted triangles that were the seal of King Solomon.
How long does Solomon's seal live?
Like many slow-growing perennials, an established Solomon's seal plant can live for many decades. In native woodland areas, some colonies are thought to be centuries old.
How is this plant best used in the landscape?
Solomon seal is generally used as a foliage plant for shady areas and is often chosen for the architectural appeal of the leaf arrangement. The flowers are not unattractive, but they are not the reason for planting Solomon's seal.
Solomon's seal combines well with bleeding hearts (Dicentra), ferns, hostas,
lungworts (Pulmonaria), pigsqueak (Bergenia), wild ginger (Asarum canadensis and A. europaeum), and astilbes. Variegated types are excellent for brightening up dark areas.
Are there other plants known as Solomon's seal?
Two plants that also are sometimes confused with Polygonatum species include Disporopsis pernyi, with glossy green foliage; and Maiathemum racemosum (false Solomon's seal) which looks very much like Polygotum, but with terminal flowers.
Is Solomon's seal invasive?
No. The plant grows and spreads rather slowly, so it's easy enough to control its spread by digging up plants that spring up from wandering roots. But the plant spreads so slowly that this is no great burden. Many people allow Solomon's seal to spread and colonize as it wishes, since few plants are easier to grow or care for.
Polygonatum. North Carolina State Extension.
Plants Poisonous to Your Pets. Deerfield Veterinary Clinic.
Solomon's Seal. University of Vermont Department of Plant and Soil Science.
Polygonatum 'Prince Charming'. Missouri Botanical Garden.
Bird, Richard. The Propagation of Hardy Perennials. Batsford Ltd. Publishing, 1994.
Solomon's Seals. Clemson Cooperative Extension.
Solomon's Seal—Poylgonatum Spp. Wisconsin Horticulture Division of Extension.