Polemonium

Polemonium is a genus of flowering plants in the family Polemoniaceae, commonly grown as ornamental perennials. The group comprises about 25 species native to temperate regions of the Northern Hemisphere, especially North America and parts of Asia and Europe. The best-known species is Polemonium reptans, commonly called Jacob's ladder, which is prized for its delicate foliage and panicles of blue flowers.

Plants are herbaceous perennials with a clump-forming to creeping habit. Leaves are typically pinnate, with 3–11 leaflets, giving a finely textured appearance. In spring or early summer, flowering stalks rise above the foliage to bear loose panicles or racemes of five-petaled flowers. Colors range from blue and purple to lavender, with white or pink forms available in some species or cultivars.

Polemoniums prefer moist, well-drained soil and a site with partial shade or protection from afternoon sun in hot climates. They are generally hardy in temperate regions and suited to borders, woodland gardens, or rock gardens. In cultivation, they appreciate regular moisture but avoid waterlogged soil; adding organic matter helps. They can spread slowly by rhizomes or self-seed.

Propagation is by seed or division in spring or fall. Some species hybridize readily in cultivation, producing a range of garden forms. Common pests are few, though powdery mildew can affect growth in humid summers. Species and cultivars vary in hardiness and cultural requirements, so gardeners typically select selections suited to their climate.