Polemonium

This group of perennials and annuals are mostly natives to North America. They grow 1 to 2 feet in height and produce pretty flowers during the spring and summer. P. caeruleum, Jacob's Ladder or Greek Valerian, has medium to bright green leaves that are finely divided into 17 to 27 lance-shaped leaflets. In the summer, thin stems bearing dense, terminal clusters of small, cup-shaped, lavender blue flowers shoot up. This plant looks lovely in herbaceous borders and cottage gardens. Care must be taken, however, as this plant self-sows freely. P. carneum has finely divided foliage into 11 to 19 elliptic to oval leaflets. Its pink or lilac-pink flowers are borne in early summer. P. pulcherrimum also has finely divided foliage and a profusion of bell- to cup-shaped, purple-blue flowers with white or yellow throats, in late spring and summer.

Pot Cultivation

These plants need moist, fertile, humus-rich soil that is well-drained and a position in full sun.

Propagation

These plants may be increased by seed or division in the spring or fall. Seedlings sown outdoors should be thinned to 6 inches apart so they don't become crowded.