Forms of Solomon’s Seal have been grown in British gardens for centuries and, once established, the common garden form (Polygonatum x hybridum) becomes a woodland stalwart living for decades or longer.
The rhizomes ramble a little when happy, but this is part of the charm. The common - and easiest - garden form is Polygonatum x hybridum. Beth Chatto sells many including ‘Betburg’ a variety that produces chocolate foliage in spring.
Most are two feet high or so (on average) and most have arching stems with pairs of leaves giving rise to another common name Ladder in Heaven.
The flowers, which are most often ivory-white, hang downwards in clusters from the leaf joints and they are often edged in green and slightly fragrant. Sometimes black berries appear after the flowers. There are arching double-flowered forms, others with variegated cream and green foliage and a narrow-leaved upright polygonatums as well. All are quiet performers that add structure to woodland or shady borders.
Where and how to plant
Find yourself a well-grown specimen and place in a cool position in dappled shade. Choose a place that isn’t disturbed, because the thick shoots emerge late from just below the surface and they are easily damaged in areas that are regularly dug or walked on.
They are lovers of cool soil and will not thrive in hot positions, although they don’t seem to mind dryish shade once established, especially if leaf litter covers them in autumn to provide a humus-rich mulch. Sometimes you have to move polygonatums around the garden before finding a spot they are really happy in, but they are worth it. Once a suitable area has been found, they will spread, but not invasively so.
If you do have to move them, do it in spring as they start into growth.
A good clump of Solomon’s seal takes time and patience but, once established, they are undemanding. Keep the soil moist in summer as this produces large clumps more quickly.
When to divide
Divide in spring as they buds break from the rhizomes. Chop into sections, making sure there’s a bud at the top.
Re-plant in friable, humus-rich soil or pot up and plant the following autumn.
Sawfly can strip the leaves in June and July: their larvae overwinter in the ground. Personally, I let the birds pick them off for me.
Polygonatums need equally green, cool plants to shine and you can use them with hardy British ferns, including forms of Polystichum setiferum, Polypodium australe, Dryopteris filix-mas or Dryopteris wallichianum. They also look handsome with the green and ivory-white Viridiflora tulip ‘Spring Green’. Or use them behind hostas, or among hellebores and wood anemones.
Varieties and similar, closely-related plants
In all there are sixty species found in Asia, America and Europe.
Britain has three native species. Polygonatum multiflorum (Solomon's Seal) is the most common, being found in lowland woods containing Ash and Field maple on chalk and limestone. Polygonatum odoratum (Angular Solomon's Seal) is a plant of limestone pavements and cracks, so it is disappearing. Polygonatum verticillatum (Whorled Solomon's Seal) is an uncommon plant of wooded gorges and river banks, mainly in Scotland.
There are garden forms and I have found this difficult to grow in my own garden, although those in damper, western areas of Britain, or those with a high water table, may do well with it.
Woodlanders are in vogue and several good nurseries now stock a full range of polygonatums and their close allies.
Polygonatum x hybridum (P. multiflorum x P.odoratum)
This hybrid is the most commonly grown and a robust starting point for the beginner. If you can grow this, you can move on to the more difficult with confidence. Tall, stately and strong with opposite pairs of mid-green leaves and cream, green-tipped pendent bells.
There is a not-so-vigorous variegated form with cream-white streaks called ‘Striatum’ - as well as the chocolate-foliaged ‘Betburg’. The latter’s foliage reverts to green after four weeks. There is also a double-flowered form called P. x hybridum ‘Flore Pleno’
This species is different in leaf formation. Rather than a ladder of opposite ‘rungs’ P. odoratum has alternative leaves arranged singly on dark stems. The leaves are generally more oval and in a brighter green.
The flared flowers hang in clusters of twos and threes. P. odoratum’ Flore Pleno’ has fully double flowers on a foot-high green-leaved plant, although in certain gardens this is talle (30 cm). P. odoratum var. pluriflorum 'Variegatum’ has rounded green leaves very narrowly rimmed in cream and red stems (75 cm). ’Silver Wings’ is a shorter form with blue-green foliage and large flowers. (All available from Beth Chatto).
Polygonatum falcatum ‘Variegatum’
A tall polygonatum with pointed green leaves, finely rimmed in cream-white, arranged alternatively up the stems. The flowers are large, white and bell-like. (up to 90 cm/ 3ft)
Himalayan and Asian varieties
Many polygonatums are now being sold, but many need cool roots and moisture in summer to thrive. Most have whorled, lance-shaped leaves and whorls of pink or red flowers circling the dark stems.
The upper part of the plant develops tendril when happy, so these plants could climb into shrubs. Even before tendrils, most will top a metre (39 inches) or more, and they form a tight, upright clump (try Edrom Nurseries or Crug Farm).
Polygonatum verticillatum ‘Rubrum’
A Chinese polygonatum that emerges from the ground in early spring, producing pink shoots that turn green. The whorls of narrow leaves frame pink-purple flowers.
Lily of the Valley (Convallaria) is closely related but rather invasive, so probably best avoided. However Maianthemum (previously Smilacena) is similar in structure to Solomon’s Seal, but the flowers are frothy versions of lily of the valley rather than bell-like droplets.
A variable, clump-forming woodlander with fine dark-green foliage and stems. There are some fine pink-flowered forms about.
A toughie with large green leaves topped by clotted-cream plumes of flower. Superb in shade and easy even in dryer gardens.
Where to buy
Edrom Nurseries www.edrom-nurseries.co.uk
Long Acre Plants www.plantsforshade.co.uk
Barrocott Plants www.barrocottplants.co.uk
Beth Chatto www.bethchatto.co.uk
Crug Farm www.crug-farm.co.uk
Did you know…?
The ancient name Solomon’s Seal comes from the inner markings found inside the rhizomatous roots.
If cut through vertically, to form discs, the pattern was thought to resemble Hebrew script. Herbalists used the roots to make a tincture for serious ailments and it’s still used to treat sports injuries today.
Historically, it was used an aphrodisiac too, although most gardeners are just content to admire the arching elegance of this cool ivory and green architectural plant.
Polygonatum means ‘many knees’ and the thick rhizomes bend and curve resembling knee joints.