Polemonium
These plants will grow in sun, or part shade, in retentive soil. Their natural habitats are cooler, mountainous areas, so a north facing bed is ideal. Generally pest free, but an overly dry soil will spoil the foliage.The silky cup-shaped flowers are generally, blue to purple, pink and white, in good sized clusters, during later spring through summer. Their common name Jacob's ladder, comes from the compound leaves, with their many leaflets looking rather ladder-like. Part of the Polemoniaceae family, which includes Phlox, Cantua and Collomia. The vast majority of these come from the 'New World', ie the Americas.
Those species with a short flower tube are visited mainly be bees and flies, while those with more elongate tubes have adapted to hummingbird, butterfly and moth pollination in their native lands. The one British native P. caeruleum was a rare plant of upland limestone, but has become more widespread and frequent, and in less natural habitats, as a result of escapes from cultivation.