Ornamental · Asparagaceae
Solomon's Seal
Polygonatum biflorum
Give it deep shade and rich, moist soil, and Solomon's seal arches up year after year with almost no fuss.
Full shade
Every 3–7 days
USDA 3–9
3–6 ft · 0.9–1.8 m
Overview
Solomon's seal is a woodland perennial grown for its graceful arching stems rather than any showy bloom. In spring, small bell-shaped flowers dangle in pairs along the underside of each stem, hidden under the leaves until you tip a branch up to look. It spreads slowly by rhizome to form a calm, sweeping colony in the shade.
This is a plant for the spots where little else is happy. It runs cold-hardy through a wide range of zones and asks only for shade and ground that stays moist and rich. Once it settles in, it returns on its own each year, taller and fuller, with almost nothing required of you.
The flowers give way to blue-black berries by late summer, which are handsome but not for eating. The young shoots are cooked and eaten in some cuisines, much like asparagus, but the berries and the rest of the raw plant are best admired and left alone.
Care
The short version: plant it in part to full shade in rich, humusy soil, keep that soil evenly moist, and otherwise leave it be to spread on its own.
Light
Solomon's seal is a shade plant through and through. It does best in part to full shade and tolerates some morning or filtered sun, but a hot, exposed spot leaves it thin and scorched.
Water
Keep the soil evenly moist, the way woodland ground stays under leaf cover. Water every 3 to 7 days in dry spells, more in the heat. An established clump shrugs off a little drought, but it always looks better with steady moisture.
Soil
Give it rich, humusy, well-drained ground worked with plenty of organic matter. It isn't fussy about pH, handling anything from 5.5 to 7.0, so the main thing is keeping the soil loose and full of compost.
Temperature
This is a tough, cold-hardy perennial that takes winters down to -40°F (-40°C) and summers up to about 86°F (30°C). The roots ride out hard freezes and push up fresh in spring.
Humidity
Ordinary outdoor humidity suits it fine, so there's no number to hit. What it really wants is the cool, moist air of a shaded bed rather than a dry, sun-baked corner.
Feeding
It's a light feeder. A balanced fertilizer in spring or a top-dressing of compost as the new shoots emerge is all it asks, and rich woodland soil may carry it with no feeding at all.
Pruning
There's little to do here. Cut the yellowed stems to the ground in late fall or after the first frost, and otherwise leave the plant to its own slow spread.
Repotting
Solomon's seal is a long-term resident that rarely needs lifting. Divide a clump only when it grows crowded and loses vigor, or when the rhizomes start shouldering up to the soil surface.
Size & spacing
A clump reaches 3 to 6 feet (91 to 183 cm) tall and spreads 2 to 4 feet (61 to 122 cm) wide over time. Give each plant room to arch out and form its colony without crowding its neighbors.
When to plant
Solomon's seal is planted, not sown in a hurry. Set out divisions or potted plants in spring or fall while the soil is cool and moist, and watch for the flowers in April and May as the new stems unfurl.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: spring or fall
- Harvest: April to May
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
Solomon's seal is an easy plant with few real problems. The two you might meet both trace back to its growing site, so reading the early signs tells you whether to deal with a pest or fix the conditions. Match what you see below and act early.
Thin, leggy stems and sparse growth
Solomon's seal stretches and thins out when it sits in too much sun or dry, worn-out soil. The leaves may scorch and yellow early in a hot, exposed spot. Move it into part to full shade, mulch and water to hold even moisture, and dig in compost to feed the worn ground.
Fix:
- Move or plant in part to full shade
- Mulch and water to keep soil evenly moist
- Amend soil with compost or organic matter
Ragged holes chewed through the leaves
This is the work of slugs and snails, which feed at night and love the cool, damp shade Solomon's seal grows in. Check for silvery slime trails to confirm them. Pick them off after dark, scatter iron phosphate bait, and clear away the leaf litter and standing moisture that give them cover.
Fix:
- Hand-pick slugs in the evening
- Use iron phosphate slug bait
- Reduce excess moisture and remove debris near plants
Toxicity
This is a low-risk plant, but it isn't fully harmless. The young shoots are cooked and eaten in some kitchens, yet the blue-black berries and the rest of the raw plant carry saponins and anthraquinones that upset the stomach. The berries are the real concern, so keep them away from children, cats, dogs, and grazing animals.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat that nibbles the foliage or swallows a berry may drool, vomit, or get loose stools. The plant isn't on the ASPCA toxic list and the risk stays low, but the berries are the part to keep out of reach.
Dogs Mild
Most dogs that chew a leaf or grab a fallen berry get away with mild stomach upset and a bout of diarrhea. It rarely turns serious, though the saponins in the plant are why curious pups shouldn't make a habit of it.
Horses Mild
Horses tend to leave the bitter foliage alone, and a small taste usually passes with nothing worse than a touch of gut upset. Keep them off the berries, where the trouble is concentrated.
Rabbits Mild
A rabbit that samples the leaves or berries can end up with a soft stool and a sour stomach. Hold off on offering any part of this plant as forage.
Livestock Mild
Grazing animals generally pass it by, and the bitter taste limits how much they eat. The saponins and anthraquinones can still bring on mild digestive upset if a hungry animal works through a patch.
Birds Mild
Wild birds eat the ripe berries and help spread the seed, but a pet bird is far smaller and can react badly to the same fruit. Steer cage birds clear of the berries and foliage.
People Caution
Only the young shoots are eaten, and then only after cooking, the way some cuisines treat them like asparagus. The blue-black berries and the raw plant hold saponins and anthraquinones that bring on nausea and diarrhea, so leave the fruit alone and keep it away from children.
Keep the ornamental berries away from pets and children; wash hands after handling.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Most Solomon's seal in gardens is the plain green species, but a few named forms are worth seeking out for size or color.
Polygonatum biflorum var. commutatum
Giant or Great Solomon's seal is the big one, throwing stout arching stems 3 to 7 feet tall that hang up to 8 or more flowers at each leaf joint.
Polygonatum odoratum var. pluriflorum Variegatum
This variegated form is grown for its foliage, with light green leaves cleanly edged in white and fragrant flowers that earn it a place in the shade garden.
Polygonatum humile
Dwarf Solomon's seal is a low Asian species that tops out around 8 to 12 inches, the right scale for a small shade bed or the front of a border.
Companions
Solomon's seal belongs in the shade garden, beside the moisture-loving woodland plants that share its cool, dappled corner.
Plant near
Ferns: Share the same moist, shady woodland conditions and contrast in texture.
Hostas: Thrive in the same rich, shaded soil and complement the arching habit.
Astilbe: Enjoys similar moist shade and adds flower color beneath the foliage.
Wild ginger: A low woodland groundcover that pairs well in cool, dappled shade.
How to propagate
Solomon's seal is simple to multiply, whether you split an existing clump for quick results or grow it from seed and wait out the slow path.
DivisionEasy
Spring or fall · 1 to 2 growing seasons
Division is the easy, dependable way to make more. In spring or fall, dig up a clump and break or cut the rhizome into pieces, leaving a growth bud on each. The new divisions settle in and fill out over 1 to 2 growing seasons.
SeedModerate
Fall (sown fresh) for cold stratification · 2 to 3 years or more
Seed takes patience. Clean the seed from ripe berries and sow it outdoors in fall so the winter cold breaks its dormancy. Even then, expect to wait 2 to 3 years or more before the plants amount to much.
Myths
True Solomon's seal and False Solomon's seal are the same plant.
They look alike at a glance but belong to different genera. True Solomon's seal (Polygonatum) hangs paired bell-shaped flowers beneath its arching stem, while False Solomon's seal (Maianthemum racemosum) carries its flowers and berries in a single plume at the stem tip. Once you know where to look, you can't mix them up.
The blue-black berries of Solomon's seal are safe to eat.
They are not. The berries are inedible and mildly toxic, holding anthraquinone that brings on vomiting and diarrhea if swallowed. Their good looks make them tempting to children, so it pays to point them out.