Polemonium reptans aka Jacob's Ladder

Polemonium reptans is a perennial wildflower in the Polemoniaceae family. Gardeners call it Jacob's ladder or Greek valerian. Its native range spans eastern Canada and the central and eastern United States. It grows in damp woods and beside shaded streams. This woodland plant forms low clumps and spreads through creeping rhizomes. It also seeds itself when growing conditions suit it.

Garden plants often reach 1–1.5 feet (0.30–0.46 metres) tall. Missouri Botanical Garden lists a spread of 1.5 feet (0.46 metres). Other sources give larger sizes, reaching about 3 feet (0.91 metres). Its green leaves are pinnate, with rows of small leaflets. Their layout gives the plant its ladder name. Lower leaves carry seven to seventeen leaflets, while upper leaves have fewer. The leaf undersides are paler and may bear fine hairs. Slender stems are light green, sometimes with a red tint. They can be weak and spread outward. The plant sheds its leaves for winter.

Loose flower clusters appear at the tips of the stems. The blooms are bell-shaped and usually pale blue. Some plants bear white flowers. Each bloom is less than 0.08 feet (0.025 metres) long. Flowering runs from April to June, though local timing varies. Bumblebees visit the flowers. The blooms stand above the divided leaves, adding spring color. Removing spent flowers can help the plant produce more blooms.

Grow it in fertile soil that holds moisture but drains well. Humus-rich loam suits it, though RHS also lists clay and chalk. It accepts acidic, neutral, and alkaline soil. Part shade is the best general choice for cultivation. It tolerates full sun where summers stay cool. Hot, humid lowland conditions can cause poor growth. Drought may send the plant into dormancy. Sources list USDA zones 3–8, with Chicago extending that range to 9. RHS rates its winter hardiness H7. Use it beneath trees, in woodland beds, or in shaded rock gardens. It also suits native plantings and containers.

Serious pest and disease problems are uncommon, but powdery mildew can occur. Spider mites may cause trouble in dry climates. Sources report resistance to deer and tolerance of black walnut. Plants For A Future records no known edible uses or hazards. That is not proof of food or pet safety. It records past medicinal uses of the roots and a plant-based hair rinse.