Known as the Cascade penstemon or coast penstemon, Penstemon serrulatus is native to the Pacific Northwest, from Oregon to Alaska. It is one of the few penstemon to occur west of the Cascade Range. It is found along streambanks and moist gullies to open rocky slopes from lowlands areas to the subalpine.
This species is semi-woody at the base, producing many upright, unbranched stems. Plants reach 50-70 cm. The leaves are mostly ovate-oblong with strongly toothed margins. The flowers are produced in terminal whorled racemes with purple to deep purple-blue, 1.5-2.5 cm long tubular flowers.
Ranges from June to August
Penstemon serrulatus is one of the easiest to grow in winter-wet climates as it prefers even moisture. Grow it in full sun to part shade in any well-drained but evenly moist soil. Unlike many penstemon, this species is not well-adapted to drought.
Cuttings may be taken in early to mid-summer. Seeds sown in autumn, will freely germinate in spring.