Plant of the Month for October 2013

Polemonium pulcherrimum
Polemonium pulcherrimum

Description and general information:

Polemonium pulcherrimum or showy Jacob's-ladder, is a tufted plant, to 30 cm, with erect to decumbent stems. Leaves are pinnately divided into 9–21 widely oval to round leaflets. The plant has a skunky smell when bruised.  Flowers are produced in terminal clusters. Individual flowers, about 2.5 cm across, are saucer-shaped and have five blue petals fused at their base.  The center of the flower is yellow. 

Plants are found in the subalpine and alpine zones (about 8,000-11,000 feet) of the western US, Alberta, BC, Yukon and Alaska, growing on gravelly soils and talus slopes.

Cultivation:

This species requires full sun in northern areas but light shade in hotter regions. If exposed to drought, plants may go summer dormant or possibly die.  Moist but well-drained soil is ideal.  If kept reasonably moist, plants will bloom throughout the growing season. Alkaline or neutral soil is best.

Bloom period:

In the wild, this species blooms late May through late July.  In milder climate, flowering commences in late March while in more northern regions, May-June is the normal flowering season.

Propagation:

Seed, division, cuttings

Seed:

Seeds require light for germination so surface-sowing is required.  Ontario Rock Garden and Hardy Plant Society suggests seeds may be directly sown at 20 C and germination will occur within 3 months. Stratification is not required.

Division:

Larger plants could potentially be dug and divided in early spring or late summer.

Cuttings:

A piece of rhizome with a tuft of leaves, may be used as cutting material.

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