Noteworthy Characteristics
Polemonium caeruleum, commonly called Jacob’s ladder, is a generally erect, clump-forming perennial that typically forms a foliage mound to 18-24” tall and as wide. Odd-pinnate compound bright green leaves (to 27 leaflets each) appear ladder-like, hence the common name. Cup-shaped, deep blue flowers with contrasting yellow stamens appear in loose, drooping, terminal clusters (cymes) in spring (April-May in the St. Louis area).
Genus name comes from the Greek name polemonion originally applied to a medicinal plant associated with Polemon of Cappadocia.
Specific epithet means sky blue in reference to the flower color.
‘Blanjou’ BRISE D'ANJOU features variegated foliage. It is a naturally occurring mutation that was discovered growing at a nursery in Brissac-Quince, France. The leaves are bright green variegated with creamy yellowish-white edges. Violet-blue flowers. U.S. Plant Patent #9,781 issued January 14, 1997.
Problems
No serious insect or disease problems. Leaf spot and powdery mildew can be problems, particularly in humid climates. Foliage may scorch in too much sun. Leaflet tips will brown up if soils are allowed to dry out. Foliage will generally decline and become less attractive as the summer progresses. Watch for slugs.
Uses
Bright foliage and blue flowers will brighten shady locations in border fronts, rock gardens, woodland gardens, cottage gardens or shade gardens.