Overview
Polemonium caeruleum is a clump forming perennial in the genus Polemonium, part of the Polemoniaceae family, with deciduous foliage. It typically grows around 0.4 m tall. Polemonium caeruleum grows best in full sun and partial shade, and tolerates most soils and any pH. Its UK hardiness is rated H7. Suggested uses include cottage and informal garden, patio and container plants and flower borders and beds. It is native to Altay, Austria, Baltic States, Belarus, Central European Russia, China South-Central, Czechia-Slovakia, East European Russia, Finland, France, Germany and Great Britain.
About
Polemonium caeruleum, known as Jacob's-ladder or Greek valerian, is a hardy perennial flowering plant. The plant produces cup-shaped, blue or white flowers.
Wikipedia contributors, CC BY-SA 4.0 — Polemonium caeruleum
About the genus
Polemonium, commonly called Jacob's ladders or Jacob's-ladders, is a genus of between 25 and 40 species of flowering plants in the family Polemoniaceae, native to cool temperate to arctic regions of the Northern Hemisphere. One species, Polemonium micranthum, also occurs in the southern Andes in South America. Many of the species grow at high altitudes, in mountainous areas.
Wikipedia contributors, "Polemonium", CC BY-SA 4.0 — Polemonium
Growing conditions
Best soil and position for Polemonium
- Sunlight
- Full sun, Partial shade
- Soil type
- Chalk, Clay, Loam, Sand
- Soil pH
- Acid, Alkaline, Neutral
- Soil moisture
- Moist but well-drained
- Aspect
- South-facing, East-facing, West-facing
- Exposure
- Exposed, Sheltered
- UK hardiness
- H7
Plant details
Polemonium caeruleum size, habit and characteristics
- Plant type
- Perennial
- Habit
- Clump forming
- Foliage
- Deciduous
- Height
- 0.4 m
- Suggested uses
- Cottage and informal garden, Patio and container plants, Flower borders and beds
- Native to
- Altay, Austria, Baltic States, Belarus, Central European Russia, China South-Central, Czechia-Slovakia, East European Russia, Finland, France, Germany, Great Britain
Care notes
Pruning and caring for Polemonium caeruleum
- Cultivation
- Prefers cool, moist conditions; avoid drought and excessive heat; mulch to retain moisture
- Pruning
- Deadhead spent flowers to prolong blooming; cut back after flowering to encourage fresh growth
- Propagation
- Divide in spring, Sow seed in cold frame in autumn or spring
- Pest resistance
- Generally pest-free
- Disease resistance
- Powdery mildews can sometimes be a problem
Frequently asked questions
How do I grow Polemonium caeruleum?
Prefers cool, moist conditions; avoid drought and excessive heat; mulch to retain moisture.
Where is the best place to plant Polemonium caeruleum?
Polemonium caeruleum prefers full sun and partial shade. It suits exposed and sheltered positions.
What soil does Polemonium caeruleum need?
Polemonium caeruleum is adaptable and grows happily in most soil types, including chalk, clay, loam and sand. It is happy in soil of any pH. Aim for soil that stays moist but well-drained.
How do I prune Polemonium caeruleum?
Deadhead spent flowers to prolong blooming; cut back after flowering to encourage fresh growth.
How big does Polemonium caeruleum grow?
Polemonium caeruleum reaches a height of 0.4 m.
Is Polemonium caeruleum hardy in the UK?
Polemonium caeruleum has an RHS hardiness rating of H7, meaning it is fully hardy throughout the UK, tolerating temperatures below -20°C.
How do I propagate Polemonium caeruleum?
Divide in spring, Sow seed in cold frame in autumn or spring.
