Polygonatum x hybridum Weihenstephan

Polygonatum Weihenstephan is not only the most vigorous and spectacular of all Solomon's seals, but it has the good taste to keep a luxuriant appearance even in summer, when its little cousins have already surrendered to the heat. It is a superb shade or semi-shade perennial plant, easy to acclimatise in the garden or even in pots. In spring, it offers gracefully arching long leafy stems, with attractive pendulous cream-white bells that give way to decorative blue-black berries. Perfectly hardy and indifferent to the presence of roots in the soil, this plant spreads as a ground cover via its rootstock, dressing the base of hedges or the edge of a grove.

Polygonatum x hybridum (synonym x intermedium) belongs to the lily family (or asparagus family according to the classification). It is the result of a spontaneous cross-breeding between two species that populate our European undergrowth: Polygonatum officinale, the fragrant Solomon's seal, and P. multiflorum, the common Solomon's seal. 'Weihenstephan' is a very beautiful and even more vigorous German cultivar.

A herbaceous and perennial plant, it develops from a fleshy ochre-coloured rootstock and in spring produces upward-angled leafy stems, both erect and trailing, reaching an average height of 1 m (3 ft) (from 80 cm (32 in) to 1.2 m (4 ft) depending on the growing conditions). This Solomon's seal will eventually form colonies covering at least 1 m (3 ft) of ground. The foliage is deciduous, with ovate leaves arranged in two opposite rows. The lamina is a shiny dark green. The leaves measure 6 to 12 cm (2 to 5 in) in length; they are lanceolate-ovate in shape and have pronounced veins. The flowering period is from April to June depending on the climate, in the form of tubular flowers with a tender green top, 1 to 2 cm (0.4 to 1 in) long, solitary or in pairs, pendulous, and born in the axil of the leaves. This nectar-rich flowering is very popular with bees but devoid of fragrance. It is followed by spherical blue-black fruits, measuring 2 to 6 mm (0.1 to 0.2 in) in diameter. The plant only goes dormant with the arrival of autumn. Solomon's seal, like lily of the valley, is a very pretty but toxic plant, so beware of budding explorers visiting your gardens!

Graceful and yet robust, and often a little slow to establish itself, this 'Weihenstephan' Solomon's seal is nevertheless faithful, lives a long time, has very few requirements, and requires little care. It tolerates the competition from the roots of trees and shrubs in moist soil. It can be planted in the undergrowth or in dappled sunlight (introduce several plants in a small area), to accompany the spring blooms of Magnolia, Kolwizia, Deutzia, spireas, lilacs, or flowering cherries. In these beds at the base of shrubs, accompany it with Anemone 'Robinsoniana', Macleayas, Anemone Blanda, and golden-yellow buttercups. In nature, Solomon's seal easily grows alongside lily of the valley. Do the same and enhance this beautiful undergrowth scene by adding daffodils, snowdrops or snowflakes, as well as blue squills, which will take over. 

The most common explanation for the name Solomon's seal comes from the appearance of the scars left on the rootstock once the flowering stems have dried, which resemble the six-pointed seal of King Solomon and King David. King Solomon is said to have also discovered the medicinal properties of Polygonatum. The distilled sap from the rootstock is still used in cosmetics today.