Polemonium caeruleum, often called Jacobs ladder is an old cottage garden favorite and a herb that was regularly used medicinally. Named after the slender, fresh green leaflets, which are arranged on the branched stems like the rungs of a ladder.
The blue version of the lovely Jacobs Ladder is an easy perennial to grow, especially for beginning gardeners and is a very attractive plant for a border with moist but well-drained soil.
The plants form a lush mound of deep green, ferny foliage, bearing upright stems with an endless succession of star-shaped blue flowers with contrasting yellow stamens.
Blooming in late spring to early summer, the bright foliage and blue flowers will brighten shady locations in border fronts, rock gardens, woodland gardens, cottage gardens or shade gardens. Both the flowers and the attractive ferny foliage are excellent for cutting.
Sowing: Sow in Autumn or Spring
Sow at 15 to 18°C (59 to 65°F) on to the surface of a moist seed sowing compost and cover lightly with vermiculite.
Germination should begin to take place after 14 days. Maintain a temperature of 15°C (59°F) after germination for the Autumn sowing and keep temperatures cool for the Spring sowings to help avoid any loss of germination, which can be caused by high temperatures.
Grow on the seedlings in light shade. When they are established, prick out each seedling as it becomes large enough to handle and transplant into 7.5cm (3in) pots or trays. Over winter in a well ventilated unheated glasshouse, tunnel or cold frame.
After the last expected frosts, gradually acclimatise to outdoor conditions for 10 to 15 days before planting out into their permanent positions, space 22 to 30cm (9 to 12in) apart.
Polemonium prefer rich, humusy, consistently moist soils, in full sun or partial shade.
Plants are intolerant of the high heat and humidity of areas with hot summers. The foliage may scorch in too much sun and leaflet tips will brown up if soils are allowed to dry out. The best performance occurs in cool summer climates.
Cut back the plants to basal foliage after blooming to tidy the planting and to encourage a possible late summer rebloom. They will self-seed in optimum growing conditions. Cut back to the base in autumn.
Jacob’s ladders generally don’t need to be divided and can be slow to recover if you try it, so consider taking stem cuttings in summer if you want to propagate your favorites. The plants can be long lived where the growing conditions are just right, elsewhere, they may fade away after a few years, so consider letting a few flower stalks set seed to get self-sown seedlings for replacements.
Shade and Woodland Gardens. Under planting of trees. Rock Gardens,
Cottage/Informal Garden, Flowers Borders and Beds or Wildflower and Wildlife Gardens
Looks good with: Hosta, Ferns, native Primula species, Dicentra.
Polemonium was used in ancient times as a remedy for fevers, palpitations and hysteria, while Ancient Greek physicians prescribed Jacob's Ladder in wine as relief from toothache, dysentery and insect bites. The main part of the plant used in medicine was the root. In the nineteenth-century it was used to treat syphilis, rabies, headaches and neuralgia. Today, the plant is not usually used medically.
Boiled in olive oil the plant makes a black dye and for some reason, cats particularly like this plant.
The plant is native to damp grasslands, woodlands, meadows and rocky areas in temperate areas of Europe.
Jacob’s ladder is rare these days in Britain and there are conservation efforts underway to save it from extinction.
In Culpeper’s day it was confined, he says to the mountain regions and Yorkshire. Since then it has been browsed by cattle and has suffered other setbacks due to human activity. In the UK it is largely restricted as a native to steep but stabilised limestone screes, usually in partial shade, but also found on debris and river-cliffs in Northumberland. It is found to sites where the soil remains moist.
The flower also known as Jacob’s ladder which is native to America, is Polemonium reptans also known as Abscess root, which actually doesn’t creep, but instead stays in somewhat loose mounds typically 30 to 45cm (12 to 18in) tall has similar-looking blooms but tends to flower a few weeks earlier.
Both are members of the Polemoniaceae family of plants, or the phlox family.
The genus name polemonium derives from the Greek polemonion, a name used for a medicinal plant associated with the philosopher Polemos of Coppadocia. The Greek polemos means 'war'. Pliny the Elder claimed that the name was taken from a war between two kings who both claimed to be the first to discover the plant's medicinal properties.
The species name caeruleum simply means ‘blue’ and refers to the colour of the flowers of the species.
The leaves give the plant its common name of Jacobs Ladder as they are divided like ladder rungs.
It is also commonly called Greek Valerian, from its historical use by ancient Greek physicians. Despite this, it is not related to the true valerian (Valeriana officinalis).
- Additional Information
Packet Size 45mg Average Seed Count 50 Seeds Family Polemoniaceae Genus Polemonium Species caeruleum Common Name Blue Jacob’s Ladder, Greek Valerian
Wildflower of Britain and Ireland
Other Common Names Jacobs ladder Hardiness Hardy Perennial Flowers Blue cup-shaped flowers Natural Flower Time June to August Height 30 to 75cm (12 to 30in) Spread 30cm (12in) Position Full sun to partial shade Soil Moist, Moderately fertile but well drained Time to Sow Sow in autumn or in spring.